To find a journal abbreviations use the CAS Source Index (CASSI) Search Tool at:
Be sure "Title or Abbreviation" is in the drop-down box, then type in journal name, check "exact match" box and click "Search." The abbreviated title will show under the full title of the journal.
If the journal is a one-word title, (e.g. Tetrahedron), then the journal name is spelled out and not abbreviated.