op. cit.
(adverb)
/ˌɒpˈsɪt//ˌɑːp-/ formal abbreviation
used by writers to avoid repeating the details of a book or article that has already been referred to
Johnson (op. cit., page 53) calls this phenomenon 'the principle of minimal effort'.
(Definition of op. cit. adverb from the Cambridge Advanced Learner's Dictionary)
cf.
(also cf ) /siːˈef/ formal
used in writing when you want the reader to make a comparison between the subject being discussed and something else
(Definition of cf. from the Cambridge Advanced Learner's Dictionary)
ff
written abbreviation for and the following pages
(Definition of ff from the Cambridge Advanced Learner's Dictionary)
sic
(adverb)
/sɪk/
a word written in brackets after a word that you have copied to show that you know it has been spelled or used wrongly
The notice outside the cinema said 'Closed on Wedensday' [sic].
(Definition of sic adverb from the Cambridge Advanced Learner's Dictionary)
ibid
(adverb)
/ˈɪb.ɪd/ specialized
used in formal writing to refer to a book or article that has already been mentioned
(Definition of ibid adverb from the Cambridge Advanced Learner's Dictionary)
--MW
(adverb)
/ˌɒpˈsɪt//ˌɑːp-/ formal abbreviation
used by writers to avoid repeating the details of a book or article that has already been referred to
Johnson (op. cit., page 53) calls this phenomenon 'the principle of minimal effort'.
(Definition of op. cit. adverb from the Cambridge Advanced Learner's Dictionary)
cf.
(also cf ) /siːˈef/ formal
used in writing when you want the reader to make a comparison between the subject being discussed and something else
(Definition of cf. from the Cambridge Advanced Learner's Dictionary)
ff
written abbreviation for and the following pages
(Definition of ff from the Cambridge Advanced Learner's Dictionary)
sic
(adverb)
/sɪk/
a word written in brackets after a word that you have copied to show that you know it has been spelled or used wrongly
The notice outside the cinema said 'Closed on Wedensday' [sic].
(Definition of sic adverb from the Cambridge Advanced Learner's Dictionary)
ibid
(adverb)
/ˈɪb.ɪd/ specialized
used in formal writing to refer to a book or article that has already been mentioned
(Definition of ibid adverb from the Cambridge Advanced Learner's Dictionary)
--MW