These are some abbreviations you might find useful when referencing, particularly if some of the details you need for a reference are missing.
Anon. - Anonymous
dir. - Director
ed(s). - editor or edition
et al. - and others (for multiple authors)
wr. - writer
prod. - producer
p. - page
pp.- pages
op. cit. - in the work already quoted
ibid. - in the same book or article etc as just quoted
n.d. - date unknown
s,l. - Place of publication unknown
s.n. - Publisher unknown