Enter a clue or pattern or both:

The Clue

Ref. books (4 letter answer)

The Answer




The answer ENCS is rarely seen, appearing only about once every 1100 puzzles.

Related Clues

Business abbrs.
Env. contents
Extras in an env.
Ltr. extras
Ref. works
Letter attachments: Abbr.
Abbr. at the bottom of a business letter
Accompaniers of cover letters: Abbr.