After working as a tutor , he arrived in Prague in 1597 .
Croll received his doctorate in medicine in 1582 at Marburg , then continued studies at Heidelberg , Strasburg , and Geneva .
After working as a tutor , Croll arrived in Prague in 1597 .
Croll received his doctorate in medicine in 1582 at Marburg , then continued studies at Heidelberg , Strasburg , and Geneva .