Johann F. C. Hessel
Videos
Johann Friedrich Christian Hessel was a German physician and professor of mineralogy at the University of Marburg.
Nineteenth century drawing of Johann Friedrich Christian Hessel
Evgraf Fedorov
Videos
Evgraf Stepanovich Fedorov was a Russian mathematician, crystallographer and mineralogist.
Evgraf Stepanovich Fedorov
Evgraf Fjodorow Strasse