Martin Gardner attributes this puzzle to Jaime Poniachik.
Puzzle and Goal
An unsolved puzzle consists of a portion of a chessboard. Some squares contain numbers while others are marked for locating pieces.
The goal is to place chess pieces (usually one of each non-pawn piece) into the marked squares to satisfy the clues.
The solved grid must satisfy the following conditions:
Using standard attack rules, each numbered clue indicates how many chess pieces are threatening it.