Related Clues:
- Work containing about 2.5 million quotations: Abbr.
- Many-vol. lexicon
- Something inside an env.
- Bus. letter abbr.
- Hefty ref.
- SASE, for one
- 125 Across, e.g.
- End-of-letter letters
- Huge reference: Abbr.
- Its first two vols. covered 43-Across
- Heavy ref. work
- Multivolume ref., usually
- Brit. ref. book
- British ref.
- Ref. that added the word 'anally' in 2010