Section 3
Citation styles

There are two levels in acknowledging source material.

  • The last section explained cases for which source material must be acknowledged.
  • This section explains how an acknowledgement can be presented.

1. Numbered references
2. Harvard style
3. Citation in the text
4. Information for each discipline



Section 3-1
Numbered references

A number is given sequentially in the text, and the reference is given at the end. Some examples are given below. The styles differ slightly across disciplines, and are therefore mixed in the examples below; students should consult their departments or refer to the discipline-specific websites for advice.

The laws of motion were first given by Newton [1], while the extension to high speeds was first proposed by Einstein [2].

[1] I Newton, Philosophiae Naturalis Principia Mathematica, 1st ed. (Streater, London 1687); see also the modern English translation, A Motte (later revised by A Cajori), Sir Isaac Newton's Mathematical Principles of Natural Philosophy (Univ of California Press, Berkeley and Los Angeles, 1934; paperback 1962).
[2] A Einstein, Ann. Phys. (Germany), 17, 891-921 (1905).


One of the most widely used collections of canned programs is the Statistical Package for the Social Sciences (SPSS) [1].

[1] Nie, N.H., Hull, C.H., Jenkins, J.G., Steinbrenner, K., & Bent, D.H. Statistical Package for the Social Sciences (2nd ed.). New York: McGraw-Hill, 1975.


Social members experience various modes of control exerted over them. According to Berger, "Where human beings live or work in compact groups, in which they are personally known and to which they are tied by feeling of personal loyalty (the kind that sociologists call primary groups), very potent and simultaneously very subtle mechanisms of control are constantly brought to bear upon the actual or potential deviant. These are the mechanisms of persuasion, ridicule, gossip and opprobrium" [1].

[1] P Berger. Invitation to Sociology (London: Penguin, 1991), p 87.


在西洋社會裏,國家社會這個團體是一個明顯的也是唯一特出的群己界線。在國家裏做人民的無所逃於這團體之外,..... 在我們傳統裏群的極限是模糊不清的‘天下'..... 界線從來就是不清不楚的,..... 所以可以著手的,具體的只有己 .....」[1]

[1] 費孝通。《鄉土中國》(香港:三聯。1986), 第28 頁。

Main variations

Different styles and formats for referencing have been adopted by different publishers and learned societies; they are all correct, but be sure to stick to single convention in any piece of writing. Also, consult the main journals in your field or your department's guidelines and follow the mainstream conventions.

  • The reference number can be given in square or round brackets, or as a superscript with or without brackets, e.g.,
    The laws of motion were first given by Newton [1].

    The laws of motion were first given by Newton (1).

    The laws of motion were first given by Newton1.

    The laws of motion were first given by Newton(1).

  • The reference number can also be given before or after the punctuation.

    The laws of motion were first given by Newton [1].

    The laws of motion were first given by Newton. [1]

  • The list of references may be provided either at the end of each page (footnotes) or at the end of the paper (endnotes).

  • The name of the author may be cited as "I Newton", "I. Newton", "Newton, I" or "Newton, I." etc.

  • The names of books and/or journals may be shown in italics.

  • In the citation of journal articles, (a) sometimes only the volume is cited, sometimes both the volume and issue number are cited; (b) either the beginning page number is given, or both the beginning and ending page numbers are given; (c) the volume and number, page number and year may be cited in different orders, and the volume number in particular may be shown in italics, bold face or underlined; (d) the title of the journal article may or may not be included.

  • For books, the publisher, place of publication and year may be shown in different orders.


The main difficulty with this style is that numbering is completely disrupted whenever a reference is added or removed. As word processing software usually can handle such numbering automatically, the style is increasingly used.


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