Complex sentence: Between the date of its official printing and 1660, the work was reprinted eighteen times in many languages; this popularity of the text led Rudolf Hirsch (a book scholar) in 1950 to call the book one of the Middle Ages' "best sellers".
Split into simpler sentences: Between the date of its official printing and 1660, the work was reprinted eighteen times in many languages. The popularity of the text and the number of times that it was reprinted led Rudolf Hirsch (a book scholar) in 1950 to call the book one of the Middle Ages' "best sellers".