Ruy López de Segura, a priest and a famous Spanish chess player of the 16th century, wrote a book of 150 pages, called Libro del Ajedrez, about exhaustive studies he made on the opening (1. e4 e5 2. ♘f3 ♘c6 3. ♗b5) that is named after him.
Source: tatoeba (9967621)