Ibid., op. cit. and Loc. cit.

Footnotes and/or reference lists may contain the abbreviations Ibid. and/or op. cit.

DEFINITIONS

1.      Ibid. (abbreviation for the Latin Ibidem, meaning "The same"). Refers to the same author and source (e.g., book, journal) in the immediately preceding reference.

2.      op. cit. (abbreviation for the Latin opus citatum, meaning "the work cited"). Refers to the reference listed earlier by the same author. 

3.      Ibid. refers to the immediately preceding reference; 

4.      op. cit. refers to the prior reference by the same author.

EXAMPLES

1.        R. Poirer, "Learning physics," (Academic, New York, 1993), p. 4.

2.        Ibid., p. 9.

3.        T. Eliot, "Astrophysics," (Springer, Berlin, 1989), p. 141.

4.        R. Builder, J Phys Chem 20(3) 1654-57, 1991.

5.        Eliot, op. cit., p.148.

IDENTIFYING THE SOURCE

·           Where Ibid. appears, the source is listed in the immediately preceeding reference. 

For reference # 2 in the list above, the source is listed in # 1 (Poirer, "Learning Physics").

·           Where op. cit. appears, the source is listed in the previous reference by the same author. 

For reference # 5 in the list above, the author is Eliot and reference # 3 is by Eliot so the source is "Astrophysics".

Loc. cit.

Loc. cit. (Latin, short for loco citato, meaning "in the place cited") is a footnote or endnote term used to repeat the title and page number for a given work (and author). Loc. cit. is used in place of ibid. when the reference is not only to the work immediately preceding, but also refers to the same page. Loc. cit. is also used instead of op. cit. when reference is made to a work previously cited and to the same page in that work. As such, loc. cit. is never followed by volume or page numbers.

EXAMPLE 1

1.      R. Millan, "Art of Latin grammar" (Academic, New York, 1997), p. 23.

2.      Loc. cit.

In the above example, the loc. cit. in reference # 2 refers to reference # 1 in its entirety, including page number. Note that loc. cit. is capitalized in this instance.

EXAMPLE 2

3.      R. Millan, "Art of Latin grammar" (Academic, New York, 1997), p. 23.

4.      G. Wiki, "Blah and its uses" (Blah Ltd., Old York, 2000), p. 12.

5.      Millan, loc. cit.

In the second example, the loc. cit. in reference #5 refers to reference # 3, including page number.