It was the first book to bear the names of its publishers, Johann Fust and Peter Schöffer. They were believed to be the first printers for a long time. The truth was discovered thanks to an anniversary, as the descendants of Schöffer decided to celebrate the anniversary of his invention. They hired a special archivist and commissioned him to study all the surviving documents. The archivist went to work scrupulously and eventually discovered the account of a lawsuit. The plaintiff Johann Fust demanded a debt from Johannes Gutenberg and seized his print shop as payment for the debt. He had to disillusion his descendants — Schöffer did not invent anything on his own, but only served as a senior assistant to the real printer — Gutenberg. And before the Book of Psalms, Gutenberg printed the Latin grammar by Aelius Donatus, several papal pardons, and two Bibles.