Check CASSI if you do not know what the abbreviation means.
CASSI lists over 1,200 chemistry journals BY THEIR ABBREVIATION
CASSI is a 3 volume set, kept on the circulation desk in the library
Distinguish author's initials from the journal abbreviation: A Smith; Jones, R, Field, W J Phys Lett 23(2)3401(1974)
(this is not Field W J
  in   Phys Lett
its Field W  
in   J Phys Lett !!)
Has part of the journal title been omitted? The Section : Acta Crys ...........Acta Crys
D
A word : ( e.g. Journal) Phys Chem ..........
J Phys Chem
Has an alternate name been used?
Happens a lot with `classic' journals - names have changed over time Chem Ber = Ber = Ber Deut Chem Ges
Comptes Rendu = C R Hebdomadaire = C. R. de Seances Acad Sci
CHECK VOLUME/YEAR CORRESPONDENCE
Does it make sense? J Am Chem Soc 16 (1994) ......
(should be vol 116)
tips:
Check other footnotes for the journal in the same article
(if JACS 1993 is v.115 - thats a clue!)
Check CASSI - it lists volume and year a journal began
CHECK ALL NUMBERS - COULD THEY BE TRANSPOSED?
476 could be 746
REMEMBER THE CITING CONVENTIONS
Ibid is NOT a journal title (Ibid = the same - the jnl just cited)
op cit is NOT a journal title
(op cit = the work (opus) cited previously)