C.922-C.928 (Merck & Co. Inc.): Merck was one of the companies licensed by the NRDC in the early 1960s to work on the production of the Cephalosporin C nucleus. Correspondence regarding research on Cephalosporin C and other antibiotics, 1950, 1953, 1958-1981.

C.929-C.940 (Microbiological Research Station, Porton Down): The station supplied microorganisms and microbial products to research workers. In 1961 it began a Cephalosporin C production project to assist with the research programme overseen by the NRDC. Correspondence, with copies of reports, regarding work on Cephalosporin C and B-lactamases, 1948, 1950, 1956-1978, 1992. Mostly 1959-1978.

C.941-C.943 (Chas. Pfizer & Co. Inc.): Pfizer was one of the companies licensed by the NRDC in the early 1960s to work on the production of the Cephalosporin nucleus. Correspondence regarding research on Cephalosporin C and other antibiotics, 1960-1962, 1977, 1978, 1985, 1986. Mostly 1960-1962.