Referencing systems

The main difference between the author–date and the notation systems is the use of a unique number for each reference in the notation system:

In-text: The GDC considered 2012 to be a very successful year (GDC 2012).
Reference list: GDC (Grains Development Council) (2012). Annual report: 2012, GDC, Canberra.

In-text: The GDC considered 2012 to be a very successful year.1
Reference list: 1. Grains Development Council. Annual report: 2012. Canberra: GDC, 2012

Both systems have numerous variations that differ in formatting details (eg punctuation, use of italic and roman type, level of abbreviation of the text).

Author–date referencing

In the Harvard system, a work is cited in the text using the author name and year of publication. In the reference list, the author name and year of publication are the first 2 elements of a reference, and references are listed alphabetically by author name. A reference list may appear at the end of each chapter or section, or at the end of the whole work.

Many reference styles are based on this system, including that of the Australian Government style manual (6th edition) and the American Psychological Association (APA).

The author–date style described in the Chicago manual of style is widely used in history and economics, and that of the Modern Language Association (MLA) in the arts and humanities – particularly English studies, literary studies, languages, cultural studies, drama, theatre, film and TV.

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Notational referencing

In the notation system, works are referred to in the text by numbers (eg superscripted or bracketed) and listed sequentially by number at the end of the work or the bottom of a page. The notation system can be further divided into the Vancouver system (citation–sequence – references are numbered in the list in the order they first appear in the text; or citation–name – references in the list are numbered in alphabetical order by author) and the Oxford (documentary-note) system.

The Oxford system differs from the Vancouver system in allowing each notation to include more than 1 reference, as well as, for example, explanatory information that is not essential to the text.

Many medical journals use the Vancouver system; see the International Committee of Medical Journal Editors and the National Library of Medicine (NLM) for details.

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Variations in author–date and notation systems

The order of the components of a reference, particularly of the year of publication, the punctuation between the components, and the font weight (bold, normal) and style (italic, roman) have traditionally been applied quite differently in Harvard and notation referencing systems. The table below shows the styling of a journal article using different referencing systems and styles.

Referencing system

Styled reference


Harvard – AMOS

Griffith GP, Hop H, Vihtakari M, Wold A, Kalhagen K & Wing Gabrielsen G (2019). Ecological resilience of Arctic marine food webs to climate change. Nature Climate Change 9:868–872.

All authors listed

Minimal punctuation


Harvard – Australian Government style manual

Griffith, GP, Hop, H, Vihtakari, M, Wold, A, Kalhagen, K & Wing Gabrielsen, G 2019, ‘Ecological resilience of Arctic marine food webs to climate change’, Nature Climate Change, vol. 9, pp. 868–72.

Heavily punctuated


Harvard – APA

Griffith, G.P., Hop, H., Vihtakari, M., Wold A., Kalhagen, K., & Wing Gabrielsen, G. (2019). Ecological resilience of Arctic marine food webs to climate change. Nature Climate Change, 9, 868–872.

Author names heavily punctuated


Harvard – MLA

Griffith, Gary et al. “Ecological Resilience of Arctic Marine Food Webs to Climate Change.” Nature Climate Change, vol. 9, 2019, pp. 868-872.

First name in full

Double quotes and maximal capitals for article title

Vancouver – citation–sequence – NLM

1. Griffith GP, Hop H, Vihtakari, M, Wold A, Kalhagen K, Wing Gabrielsen G. Ecological resilience of Arctic marine food webs to climate change. Nat. Clim. Chang. 2019 Oct;9:868-72.

All authors given, or reduced to 3 or 6 followed by ‘et al’ or ‘and others’

Abbreviated journal title, roman 

Publication date after journal title

Oxford – Australian Government style manual

1. GP Griffith, H Hop, M Vihtakari, A Wold, K Kalhagen & G Wing Gabrielsen, ‘Ecological resilience of Arctic marine food webs to climate change’, Nature Climate Change, vol. 9, 2019, pp. 868–72.

Initial precedes family name

Single quotes for article name

Publication year after volume number

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