 In the meantime (1827) his father had received a call as professor of history to Munich and Guido, influenced by his father's lectures, took up history as his chief study.The fruit of these studies where "Nikolaus von der Flüe" (Ratisbon, 1831) and "Die Jungfrau von Orleans" (Ratisbon, 1834; 3rd ed., 1895).Jointly with Count Franz Pocci, he published from 1834-39 an illustrated serial on the festivals of the Church, the "Festkalender in Bildern und Liedern", the first illustrated magazine for the young in German.