1. Identification and differentiation of propionibacteria by electrophoresis of their proteins;Baer;Milchwissenschaft,1987
2. Identification rapide des bactéries propioniques;Baer;Schweiz. Milchw. Forschung,1988
3. Manual of Determinative Bacteriology;Bergey,1930
4. Bergey's Manual of Determinative Bacteriology,1957