"Hornbook" is a word in ENGLISH

The first book for children, or that from which in former
times they learned their letters and rudiments; -- so called because a
sheet of horn covered the small, thin board of oak, or the slip of
paper, on which the alphabet, digits, and often the Lord's Prayer, were
written or printed; a primer.

A book containing the rudiments of any science or branch
of knowledge; a manual; a handbook.