• Reference citations are each numbered in sequential order as they appear in the text. References that appear only in boxes, tables, or figures should be numbered last. In Focus pieces will contain a separate numbered reference list.
  • When cited in the text, reference numbers are superscript, not in parentheses, unless they are likely to be confused with another number (e.g., 4 km (ref. 2)).
  • Only one reference should be assigned to each number, and it will appear only once in the reference list (but may appear multiple times within the text).
  • If a reference is cited more than once in the text, repeat the number for that reference within the text
  • When text requires more than one citation, list superscripts separated by comma and no space, like this: 1,7-14
  • The reference number appears after any punctuation (e.g., According to Miller,14 the best theory comes from Sarta and colleagues.22).
  • Remember that ‘et al.’ (no preceding comma) must be used in conjunction with the first named author. If you want to refer to the principal author in the text and he or she is not the first named, the principal’s name should be followed by “and colleagues” or “and collaborators.”

In preparing reference lists, please ensure that:

  • Authors are listed surname first, followed by a comma and initials of given names. There are no periods after initials. All authors are included in reference lists unless there are more than five, in which case the first author is followed by ‘et al.’. Use an ampersand (&) before the last name in the reference; there is no comma before the ampersand. Periods do not follow initials unless directly before article title.
  • Titles of all cited articles are given in upright, not italic text. The first word of the title is capitalized, the title written exactly as it appears in the work cited, ending with a full stop. There should be a period after article titles. No period after book or journal titles.
  • Book titles are italic with all main words capitalized. Journal titles are italic and written out in full (no abbreviation). But when referring to symposia use the common contractions: Symp., Proc., Assoc., Soc., but leave more obscure words unaltered (see example in list below).
  • Volume number follows the journal title. Do not list issue number. The publisher and city of publication are required for books. Comma between volume number and page number.
  • Use the abbreviations: ed/eds; Ch.; Vol.; 1st edn (no full point).
  • Second line of text is not indented.
  • References to online-only journals are in the style: authors, article title, and journal name as above, followed by URL – or doi if known – and the year of publication in parentheses.
  • References to websites are in the following style: Author. Title of Paper Website title [online] (YEAR) Complete URL should be sufficient to completely define the reference document. If the author mentions the same website many times in the paper as a source of information, and it would be unreasonable to type out the URL every time, it may be given a number and put in the reference list. Alternatively, if it has a ‘name’ (for example, John Smith’s website) you may say ‘see John Smith’s website ( at first use and then simply refer to it as ‘John Smith’s website’ thereafter.
  • Patents should be cited in the reference list as: author’s name, title of patent, type of patent and number, year (in parentheses). See example below.
  • If the author does not cite within text, leave reference list in alphabetical order (but authors should cite in text).
  • In reference lists, page ranges use all digits, e.g., 208–212 (not 208-12)
  • Foreign-language titles are Sentence style; initial cap only those words that would be capped in the language.


Journal Article:

  1. Kaufmann-Heemels, AT, Jennings, C & Carr, K. Where to publish a Nature reject. Proceedings of the National Academy of Sciences 73, 208–212 (1996).
  2. Clarke, M. Keep it short. Journal of Cell Biology Abstracts 21, 789 (1991).
  3. Diener, E & Seligman, MEP. Beyond money: toward an economy of well-being. Psychological Science in the Public Interest 5 (2004).
  4. Bentley, DR et al. Accurate whole human genome sequencing using reversible terminator chemistry. Nature 456, 53–59 (2008).


  1. Tromans, A. How to Edit a Manuscript 1–44 (Bourne and Hollingsworth, London, 1922).

Popular article:

  1. Dworkin, R. The ‘devastating’ decision. New York Review of Books (February 2010).

Edited Volume:

  1. Kasser, T & Kanner, AD, eds. Psychology and Consumer Culture: The Struggle for a Good Life in a Materialistic World (American Psychological Association, Washington DC, 2004).

Chapter in Edited Volume:

  1. Wenz, C et al. in The Production Nightmare 2nd edn, Vol. 56 (Whittock, K et al., eds), Ch. 8, 222–333 (Academic, New York, 1935).
  2. Haines, N & Cotter, R in Studies in Manic Depression Vol. 1 (Tallack, P, ed), Ch. 2 (Oxford University Press, Oxford, 1982).


  1. Shadwell, J in Proc. 4th Int. Symp. Transylvanian Fish. Soc. 2nd edn (Howlett, R & Thomas, A, eds), Part II, 4–5 (Springer, Berlin, in press).


  1. Report No. 12345–67, 445–449 (National Academy of Sciences, Washington DC, 1988).


  1. Bates, N. New way for processing guests in motels. European patent 5,567,258 (1963).


  1. New Economy Working Group [online].
  2. Friends of the Cheat. North Fork Greens Run [online] (2010).

Online article

  1. Alexander, LV. Updated precipitation series of the UK. Atmospheric Science Letters [online] 1, 142–150 (2000) (doi:10.1006/asle.2001.0025).
  2. Li, R, Zhu, H & Wang, J. De novo assembly of human genomes with massively parallel short read sequencing. Genome doi:10.1101/gr.097261.109 (in press).

Online Poll

  1. Center for a New American Dream. New American Dream: A Public Opinion Poll [online] (2004).


  1. Nishimura, Y et al. The 1843 tsunami deposits found in the peat deposit at Kiritappu marsh [in Japanese with English abstract]. Daiyonki Kenkyu 39, 451–460 (2000).

Personal Communication

  1. Clark, J. Personal communication, spring 2006.