Janko.at attributes this puzzle to Adolfo Zanellati.
Puzzle and Goal
An unsolved puzzle consists of a square grid. Some cells have numbers or letters in them.
The goal is to place a number and a letter in each cell to satisfy the clues.
The solved grid must satisfy the following conditions:
Each number appears in each rank.
Each letter appears in each rank.
Each letter-number combination appears once in the grid.