short for the Latin "Ibidem", meaning "The same".
Refers to the same author and source (e.g. book, journal) as the immediately preceding reference.
Short for the latin "opus citatum", meaning "the work cited".
Used in footnotes to refer the reader to an earlier citation.
(ibid refers readers to the immediately preceding citation.)
4. R. Poirer, "Learning physics," (Academic, New York, 1993), p. 4.
5. Ibid, p. 9.
6. T. Eliot, "Astrophysics," (Springer, Berlin, 1989), p. 141.
7. R. Builder J Phys Chem 20(3) 1654-57 1991.
8. Eliot, op. cit., p.148.
TRACKING DOWN THE SOURCE
If you see Ibid look at the reference right before it to identify the source.
For No. 5, the source is listed in No 4. (Poirer, "Learning Physics")
If you see op. cit. look at the ALL of the previous footnotes to find the author. The source you want is listed there.
For No. 8 we see that No. 6 is by Eliot so the source is "Astrophysics"
Another common abbreviation seen in reference lists only is 'op cit', which means 'in the work cited'. This is used when referring back to a work cited earlier in the paper, where this is not the most recently used citation.
"...as noted by (Hedley, 1978, p.29). A more theoretical view is offered by Scwartz (1993), however it could be argued that this view is influenced by the bias of the researcher (Hedley, op cit)..."
In the reference list, op cit is used to avoid repeating the same details:
Harris, P. (1997). The fear of dying. In D. Forster (Ed.). Beareavement and loss (2nd edition, pp.94-100). London: Macmillan.
Dollar, G. (1988). Pyscho-social perspectives of ageing. California: Sage.
Sullivan, C. (1997) The role of the child. In D. Forster, op cit (pp.131-154).