Hildenbrand G; Cohen, Marcus A. (1998). "An appraisal of the life and work of Dr. Josef Maria Issels 1907–1997". J Altern Complement Med. 4 (2): 137–40. doi:10.1089/acm.1998.4.137. PMID9628203.
Hildenbrand G; Cohen, Marcus A. (1998). "An appraisal of the life and work of Dr. Josef Maria Issels 1907–1997". J Altern Complement Med. 4 (2): 137–40. doi:10.1089/acm.1998.4.137. PMID9628203.