Related Clues:

• Direct mail abbr.
• It may fill a lib. shelf
• Multivolume ref. work
• S.A.S.E., e.g.
• Philologist's ref.
• Set of Brit. tomes
• Went around
• Env. contents
• Business letter abbr.
• Letter abbr.
• Ref. work
• Bottom-of-letter abbr.
• Voluminous ref. set
• Multivolume ref.
• Ref. tome