 Complete the following phrase:  At age fourteen, Petri was enrolled at the Dresden Academy of Fine Arts where he would remain for eleven years under the tutelage and guidance of Adrian Ludwig Richter and Julius Hübner. Petri won six awards and a scholarship to a further education in Italy, upon completion of which he was to return to the Dresden institution as an instructor. Petri was unable to accept the offer due to physical frailty. Hermann Lungkwitz, who married Petris sister Elisabeth, befriended Petri while at the Dresden academy. Petri and Lungwitz joined other students in the failed 1849 