My father-in-law was held in Stalag XVIIIC until his successful escape in April 1945. In his diary that he kept during the war he mentions being taken from the stalag to Mittenburg for 2 weeks. My research would indicate that he was therefore at Nordhausen, which seems a long way to take a work party for only 2 weeks. Near to Markt Pongau is a town called Mitterberg, does a simple misspelling sound more probable. Evadeus