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Citation Styles and How to Guide

Citation Guidance




The Council of Science Editors (CSE) was formerly known as the Council of Biology Editors (CBE).  CSE reference lists require users to abbreviate the journal titles and use unique formatting for author(s) initials.  CSE has three major systems (Citation-Sequence; Citation-Name; and Name-Year).  Each system uses a different style variation for in-text citations and how your reference list is organized. This guide will review the Name-Year citation style for sources of information. For more questions, please see the CSE Citation Quick Guide developed by Dalhousie University. Most of the information in this Libguide has been garnered from this Citation Guide. 

Dalhousie University CSE Citation Style-Quick Guide


General Rules

When citing a journal, use the official abbreviation of its title.Use only one period at the end of the journal abbreviation.
e.g., Can J Fish Aquat Sci. Mol Cell Biol. Forest Ecol Manag.
However, if the journal title consists of one word, there is no need to abbreviate it.
e.g., Science. Nature. Bioscience.

When citing the title of a book or chapter, or an article title, capitalize the first word and any proper nouns or adjectives. Subtitles and all other words should be in lower case letters.
e.g., Wetland ecology: principles and conservation.

Each author name is presented with the last name first, followed by a space, and then the author initial(s) as given (but without periods).
e.g., Fazli Wahid → Wahid F You Young Kim → Kim YY

Within a reference, list author names in the same order as they are listed on the article or book. This reflects the amount of work each researcher contributed. The author whose name appears first is known as the “first author” or “primary author”. Separate multiple author names with commas.
e.g., Wahid F, Shehzad A, Khan T, Kim YY.

Letters should match exactly how they are listed (including uppercase, lowercase, hyphens, and diacritics).
e.g., Irene de la Cruz-Pavía → de la Cruz-Pavía I Yu-Ting Chen → Chen Y-T
Mónica De la Fuente → De la Fuente M Long-Fang O. Chen → Chen L-FO

Sometimes the author is an organization or a government body (instead of personal names). An acceptable abbreviation enclosed within square brackets can precede the full name. This will shorten an in-text citation but still be alphabetized in the list of references as starting with “Canadian” 
e.g., Canadian Wildlife Federation. [CWF] Canadian Wildlife Federation.

Write the Latin or scientific names of organisms in capitalized italics (for the Genus) and lowercase italics (for the species):
e.g., Drosophila Salmo salar Pinus ponderosa Rosa rugosa
When using the names of higher orders and families, capitalize the name but do not italicize:
e.g., Lepidoptera Cetacea Ranunculaceae Falconidae

For books and journal articles list the year only.
e.g., 2019.
For any medium or activity that is more specifically time sensitive, include the month using the first three letters, followed by the day.
e.g., 2011 May 2.
Most website content can be changed in real time. This makes it challenging to determine when the content you are viewing was first published or last edited. For this reason, it is important to provide the exact date when you accessed and retrieved this kind of information.
e.g., [accessed 2016 Aug 24].
For website content without a stated date, look for a copyright date (in the footer near the very bottom). This date can be used with the letter “c” in front of the year. Another option, if the information is obviously up to date, is to use the current year. When no date can be discerned, state that the date is unknown.
e.g., c2020. 2022. [date unknown].

For non-print items that use special equipment to read them, a medium designator is required in the reference. Include it in square brackets after the item title.
e.g., [DVD]. [microfiche]. [podcast]. [video].

For specialized subject matter, a content designator is optional in the reference. These informative labels provide a helpful context and can be included after the item title in square brackets.
e.g., [dissertation]. [editorial]. [image]. [map].

For Canadian provinces and American states, use the two-letter postal abbreviation.
e.g., Toronto (ON): Cambridge (MA):
For other countries, use the name as it is listed within the publication. Each country name can be spelled out or listed using the 2-letter ISO country code.
e.g., Oxford (England): Oxford (UK): Delhi (India): Nairobi (KE):
Two large publishing cities are exceptions and do not require the country or state.
e.g., London: New York:

DOI: Stands for “digital object identifier” and begins with the number “10”. If a DOI exists, it should be included at the end of the citation, using the URL format of “”.
e.g., If the DOI is 10.1371/journal.pone.0266938, use this URL format:

Note that there are no spaces between these numbers.
e.g., 244(2):
All journals have a volume number but not all journals have a single-issue number. If issues are combined, include both numbers. If there is no issue number, list the volume only.
e.g., 51(3-4): 607:

These numbers may or may not be obvious. Download the document or article as a PDF if this format is available and record the specific range of page numbers.
e.g., 604-612.
Include any prefix with the page number(s). In this example, the letter “S” stands for a journal supplement.
e.g., S9-S11.
If the first page is numbered page 1, the page numbers most likely correspond to the PDF and not the journal or the book. In this case, indicate the total number of pages using the notation [about # p.].
e.g., [about 11 p.].
This “about” notation indicates the length of the item, recognizing that enlarging or decreasing the font size or page magnification when printing the document may change the total number of pages.

Some journal articles are assigned a document or article number. This reflects the emerging digital publishing environment when articles are numbered individually. If so, include it using the format of a lowercase “e” in front of the document number, followed by the number of pages.
e.g., volume number(issue number):eDocument. [about # p.]. 17(5):e0266938. [about 14 p.].
Sometimes the DOI may include the article number. This occurs in the example below.
e.g., DOI: 10.1371/journal.pone.0266938 for “e0266938.”
de la Cruz-Pavía I, Westphal-Fitch G, Fitch WT, Gervain J. 2022. Seven-month-old infants detect symmetrical structures in multi-featured abstract visual patterns. PLoS ONE. 17(5):e0266938. [about 14 p.].

How to cite

Author(s) or editor(s). Year. Title. Edition. Place of publication: Publisher. Extent.
The “Extent” refers to the total number of pages or the page numbering. In a reference to an entire book, this element is optional, but in a reference to a part of a book (e.g., a chapter), the pagination of the part is required. In some cases, the extent will include the name of the part of the book, followed by its page numbers.
One author

  • Keddy PA. 2010. Wetland ecology: principles and conservation. 2nd ed. New York: Cambridge University Press.

For 2 or more authors

  • Glasner P, Rothman H. 2004. Splicing life? The new genetics and society. Aldershot (GB): Ashgate.

Chapter (part) of a book

  • Myers JH, Bazely D. 2003. Ecology and control of introduced plants. Cambridge (England): Cambridge University Press. Chapter 6,                 Introduced plant diseases; p. 147-163.

Figure or map (part) of a book

  • Bòˆrner K, Polley DE. 2014. Visual insights: a practical guide to making sense of data. Cambridge (MA): MIT Press. Figure 6.2, Science-           related Wikipedia activity; p. 174-175.

Book with editor(s)

  • Boyd IL, Bowen WD, Iverson SJ, editors. 2010. Marine mammal ecology and conservation: a handbook of techniques. Oxford (UK):                   Oxford University Press.

Chapter or article in an edited book

  • Gavito ME. 2007. Mycorrhizae and crop production in a world of rapid climate change: a warning call. In: Hamel C, Plenchette C, editors.          Mycorrhizae in crop production. Binghamton (NY): Haworth Food & Agricultural Products Press. p. 293-310.

Note: In this example, ME Gavito is the author of the article called ‘Mycorrhizae and crop production in a world of rapid climate change: a warning call’ which can be found on pages 293-310 in a book called ‘Mycorrhizae in crop production’ which was edited by C Hamel and C Plenchette.
Organization or government body as author

  • [CWF] Canadian Wildlife Federation. Land-use planning: an ecological approach. 1969. Ottawa (ON): Canadian Wildlife Federation.

Entry in an encyclopedia or dictionary with author(s)

  • Zonn IS, Glantz MH, Kostianoy AG, Kosarev AN. 2009. The Aral Sea encyclopedia. Berlin (Germany): Springer. Chokolak; p. 71.

Entry in an encyclopedia or dictionary with editor(s)

  • Sternberg G, editor. 2004. Native trees for North American landscapes. Portland (OR): Timber Press. Acer saccharum [sugar maple]; p.           56-59.

No author(s) and no editor(s): Use the title as the initial element

  • McGraw-Hill dictionary of scientific and technical terms. 6th ed. 2002. New York: McGraw Hill. Chamois (Rupicapra rupicapra); p. 365.

Author(s). Year. Article title. Journal Title Abbrev. volume number(issue number):inclusive pages. URL.
Author(s). Year. Article title. Journal Title Abbrev. volume number(issue number):eDocument. [about # p.]. URL.
For journals without issue numbers, use: volume number:inclusive pages. OR volume number:eDocument.
If a DOI exists, include it at the end of the citation, written in the format of “”.
Do not just copy and paste the URL for the journal article from your browser, especially if it contains “ezproxy”.
Incorrect URL:
Correct URL:
Check your URL by placing it into a browser (it should take you to the article without requiring authentication).

One author

  • MacRae TH. 1997. Tubulin post-translational modifications: enzymes and their mechanisms of action. Eur J Biochem. 244(2):265-278.  

For 2 to 10 authors: List all authors.

  • Srivastava DS, Staicer CA, Freedman B. 1995. Aquatic vegetation of Nova Scotian lakes differing in acidity and trophic status. Aquat Bot.         51(3-4):181-196.

More than 10 authors: List the first 10 author names, followed by “et al.”.

  • Adl SM, Leander BS, Simpson AGB, Archibald JM, Anderson OR, Bass D, Bowser SS, Brugerolle G, Farmer MA, Karpov S, et al. 2007.             Diversity, nomenclature, and taxonomy of protists. Syst Biol. 56(4):684-689.

Article in a journal without issue numbers: Use volume number:inclusive pages. OR volume number:eDocument.

  • Hong B, Grzech D, Caputi L, Sonawane P, Rodríguez López CE, Kamileen MO, Hernández Lozada NJ, Grabe V, O’Connor SE. 2022.               Biosynthesis of strychnine. Nature. 607:617-622.

Article in a journal supplement: A supplement identifier follows the issue number and pages include the letter “S”.

  • Savage N. 2011. Fuel options: the ideal biofuel. Nature. 474(7352 Suppl):S9-S11.

Online article (when you know specific page numbers)

  • Wahid F, Shehzad A, Khan T, Kim YY. 2010. MicroRNAs: synthesis, mechanism, function, and recent clinical trials. Biochim Biophys Acta         Mol Cell Res. 1803(11):1231-1243.

Online article (when the PDF starts on page 1)

  • Fishman J, Taylor L, Frank I. 2016. Awareness of HPV and uptake of vaccination in a high-risk population. Pediatrics. 138(2):e20152048.           [about 11 p.].

Online article (when there is no PDF and no DOI): For this kind of article, include your access date.

  • McDaniel CJ, Crowder LB, Priddy JA. 2000. Spatial dynamics of sea turtle abundance and shrimping intensity in the U.S. Gulf of Mexico.           Ecol Soc. [accessed 2016 Aug 24]; 4(1):e15. [about 18 p.].

Author(s) or editor(s). Year. Title. Edition. Place of publication: Publisher; [date updated; accessed date]. Notes. URL.

  • Zuur AF, Ieno EN, Smith GM. 2007. Analyzing ecological data. New York: Springer; [accessed 2016 Aug 22].             387-45972-1.

Chapter or article (contribution) in an edited e-book

  • Rehm BHA. 2015. Microbial synthesis of biodegradable polyesters: processes, products, applications. In: Fakirov, S, editor. Biodegradable            polyesters. Hoboken (NJ): John Wiley & Sons; [accessed 2020 Nov 12]. Chapter 3:47-72. [about 26 p.]. Knovel [database].

Contribution in an online encyclopedia or dictionary with author(s) and editor(s)

  • Campbell D. c2020. Wetlands. In: Goldstein MI, DellaSala DA, editors. Encyclopedia of the world's biomes. Volume 4. San Diego (CA):                Elsevier; [accessed 2020 Dec 22]. p. 99-113. [about 15 p.].

Note: A multi-volume work may have a copyright date that differs from when the entry was last updated, revised or modified. The corresponding in-text citation will use only one date, in this case (Campbell c2020). If you use the copyright date, include a lowercase “c” in front of the year.

Author(s) of paper. Year. Title of paper. In: Editor(s). Title of book. Number and name of conference; date of conference; place of conference. Place             of publication: Publisher. Extent. Notes.

  • Cameron R. 2010. Research strategy for Nova Scotia protected areas. In: Bondrup-Nielsen S, Beazley K, Bissix G, Colville D, Flemming S,        Herman T, McPherson M, Mockford S, O’Grady S, editors. Ecosystem based management: beyond boundaries. Proceedings of the 6th             International Conference of Science and the Management of Protected Areas; 2007 May 21-26; Wolfville, NS. Wolfville (NS): Science and       Management of Protected Areas Association. p. 503a-503e.


Author(s) or editor(s). Year. Title. Edition. Place of publication: Publisher. Extent. Report No.: Notes. URL.

  • Benoit A, Dykstra A, Francis C, Gould JJ, Knockwood M, Knockwood P, Levi F, Levi A, Paul C, Prosper B. 2010. Mi'kmaq knowledge of                 species at risk in New Brunswick, Nova Scotia and Prince Edward Island. Gatineau (QC): Canadian Wildlife Service. Report No.: 510.              Atlantic region.

Author. Year. Title [content designator]. Place of publication: Publisher (often a university). Extent. URL.

  • Merovitch, NH. 2016. A simple automated system for appetitive conditioning of zebrafish in their home tanks and studying underlying neural       activation [master’s thesis]. Halifax (NS): Dalhousie University. 128 p.

Author(s). Date. Article title. Full Newspaper Title. Section: first page (column).

Print newspaper article

  • Weber B. 2011 Aug 27. Caribou recovery strategy allows more development on critical oil sands habitat. Globe and Mail. Sect. A:12 (col.         2).

Online article from a newspaper database, such as Factiva or Eureka

  • Weber B. 2011 Aug 27. Caribou recovery strategy allows more development on critical oil sands habitat. Globe and Mail. [accessed 2012         Sep 5]; Sect. A:12. Factiva [database].

Note: In this example, the online version of the article did not provide a column number.
Online article from a newspaper website

  • McPhee J. 2020 Jan 21. Fundraising goal reached for Halifax wilderness park. Chronicle-Herald (Halifax, NS). [accessed 2020 Feb 27].  

Note: If the name of the newspaper is not geographically specific, add the name of the city.

Author(s). Date. Title of website. Place of publication: Publisher; [date updated; accessed date]. URL.

  • Lear L. 1998. The life and legacy of Rachel Carson: Rachel Carson’s biography. New London (CT): Linda Lear Center for Special Collections      and Archives; [accessed 2016 Aug 27].
  • Polybrominated diphenyl ethers in fish and sediment. [date unknown]. Gatineau (QC): Environment and Climate Change Canada; [modified         2020 Feb 7; accessed 2021 Dec 22].                                       indicators/polybrominated-diphenyl-ethers-fish-sediment.html.

Notes: An author name and a date may not be listed. When it looks like an organization is both author and publisher, place the organization in the publisher position. When no date is stated, look for a copyright date. This can be used with the letter “c” in front of the year. Another option, if the information is obviously up to date, is to use the current year. When no clear date can be discerned, state that the date is unknown

Author(s). Date. Title of post [medium designator]. Title of blog. [date updated; accessed date]. URL.

  • Mah C. 2012 Sep 23. Ophiothela brittle stars invade the Atlantic! [blog]. The Echinoblog. [accessed 2016 Jun 12].                                               

Title of video [medium designator]. Date posted, length. Title of program (if applicable). Producer. [accessed date]. URL. consider

  • North America's marine protected areas: protecting marine life [video]. 2012 Jun 7, 2:30 minutes. Commission for Environmental                             Cooperation.  [accessed 2012 Sep 4].


  • How trees talk to each other [video]. 2016, 18:10 minutes. TED Foundation. [accessed 2022 Aug 15].                                                                 

Author(s). Year. Title [medium designator]. Place of publication: Publisher; [date updated; accessed date]. URL.

  • Nucleotide [database]. 1988- . Accession No. NM_006538.4, Homo sapiens BCL2 like 11 (BCL2L11), transcript variant 6, mRNA. Bethesda            (MD): National Library of Medicine (US), National Center for Biotechnology Information. [updated 2018 Dec 23; accessed 2018 Dec 28].
  • Stinson K, Donohue K. 2006. Invasive species mapping at Harvard Forest 2005 [dataset]. Albuquerque (NM): US Long Term Ecological                   Research Network; [updated 2006 Feb 16; accessed 2020 Aug 22].

References to personal communications (e.g., letters, personal conversations, email messages), which are not publicly retrievable, should be placed in the body of the paper rather than listed in the references section. Example:

  • During the 2007 season, observers noted four humpback females in the bay, while the following year, only two females were seen (2009 email message from R Comeau to the author; unreferenced).

In-text citations (using the year (N-Y) system)

Within the text of your paper or document, to cite an author’s work (i.e., to paraphrase and acknowledge the source of the information), give the author(s) last names only and year. Some instructors also require page numbers (or other position designators) for information from a specific location in the cited document.

Each citation belongs inside the relevant sentence, within parentheses and before the period, but not necessarily at the end of the sentence. All sources cited in the text of a paper must be included in the list of references and all references must be cited in the text


One author   

(Beals 2019)

two authors

(Glasner and Rothman 2004)

More than two authors     

(Benoit et al. 2010)

Organization or government as author   

(Government of Canada 2021)

No author   

(McGraw-Hill dictionary…2002)

(Use the first word or first few words of the title, followed by an ellipsis.)

No date   

(Polybrominated…[date unknown])

Works by same author(s) in different years   

(Gemmrich and Garrett 2008, 2011)

Separate years with a comma.

Works by same author(s) in same year 

(Smith 2007a, 2007b)

Use lower-case letters starting with “a”.

Works by same first author in same year   

(Wackernagel, Lewan et al. 1999; Wackernagel, Onisto et al. 1999)
List enough additional authors to distinguish each article.

Works by multiple authors             

(Gemmrich and Garrett 2008, 2011; Benoit et al. 2010; Beals 2019).

Arrange sources first by year of publication and then alphabetically by author, separating authors with a semi-colon


An in-text citation should appear next to the text to which it refers. Here are several examples of where to locate an in-text citation within a sentence:

A recent review (Beals 2019) examined the nutrient density of this crop…

Studies of large surface waves in the ocean (Gemmrich and Garrett 2011, 2012) have shown tha

Smith (2007b) analyzed data on a global scale, while other case studies conducted in specific locations (Zuur et al. 2007; Keddy 2010) to demonstrate that not all statistical models were appropriate for analyzing ecological data.

Postharvest senescence impacts the overall crop value enough that studying physical, chemical, and genetic methods are worthwhile for extending shelf life (Chen et al. 2008).

In CSE, as with other styles, you signal the source through the in-text citation, placed adjacent to the idea you are citing, though not necessarily at the beginning or end of the sentence. For example:
      Gavito (2007) argued idea X, while Beals (2019) argued idea Y; however, no one has considered idea Z.
At the end of the document, you must provide a full reference list entry for each source, so the reader can locate the documents you used.

Quotations are used infrequently in academic science writing; usually, relevant material from scholarly sources is included using paraphrases. If you do use exact wording, that wording must be enclosed in quotation marks.

Paraphrases capture and express the idea in a source in your own way and words. Paraphrasing is not a rearranging of words or finding synonyms for words in the original passage; doing so will result in an inadequate paraphrase, which is a type of plagiarism.

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