1. Storage of bacteria in liquid nitrogen;Jarvis;J. Med. Lab. Technol.,1967
2. Preservation of microorganisms by liquid nitrogen refrigeration;Swoager;Am. Lab.,1972
3. Simplified storage and retrieval of stock cultures;Nagel;Appl. Microbiol.,1972
4. Preservation and storage of microorganisms in the gas phase of liquid nitrogen;Daily;Cryobiology,1973
5. Nitrogen preservation of stock cultures of unicellular and filamentous microorganisms;Dietz,1975