At Giessen his lecturers included R Baltzer, M Pasch and P A Gordan . Moritz Pasch was a geometer while Paul Gordan was famed for his work in invariant theory. However Gordan had undertaken research on abelian functions before becoming fascinated by invariant theory, and Wiltheiss went on to undertake research on that topic, making a major contribution to the theory of abelian functions.
Sa Giessen kanyang lecturers kasama Baltzer R, M Pasch at City Gordan. Moritz Pasch ay isang geometrisyan habang Paul Gordan ay sikat para sa kanyang trabaho sa invariant theory. Subalit Gordan had nagtangka pananaliksik sa abelian function bago maging nabighani ng invariant teorya, at Wiltheiss nagpunta sa magsagawa ng pananaliksik sa na topic, gumawa ng isang malaking kontribusyon sa teorya ng abelian function.