In 1922 the University of Heidelberg rejected Hermann Oberth’s doctoral dissertation on space travel. According to German Wikipedia, the reason was that there was no recognized expert on the subject. Oberth submitted the same manuscript as a diploma thesis in Klausenburg, today Cluj in Romania, and passed the state examination in 1923. In the same year the Munich publisher Oldenbourg printed it. Oberth had to pay the printing costs himself. The book became a success. From 1923 to 1938, with interruptions, he worked as a secondary school teacher in Transylvania.