In 1929, shortly before graduating from university, Rejewski began attending a secret cryptology course which opened on 15 January,[12] organized for select German-speaking mathematics students by the Polish General Staff's Cipher Bureau with the help of the Mathematics Institute's Professor Zdzisław Krygowski. The course was conducted off-campus at a military facility[13] and, as Rejewski would discover in France in 1939, "was entirely and literally based" on French General Marcel Givièrge's 1925 book, Cours de cryptographie (Cryptography Course).[14] Rejewski and fellow students Henryk Zygalski and Jerzy Różycki were among the few who could keep up with the course while balancing the demands of their normal studies.[15]