References:
Nester EW, Lederberg J. Linkage of genetic units of Bacillus subtilis in DNA transformation. Proceedings of the National Academy of Sciences of the United States of America. 1961 Jan 15;47(1):52-55. DOI: 10.1073/pnas.47.1.52 PMID: 13728419, PMCID: PMC285232
Sherwin SA, Carlton BC. Suppression of Tryptophan Mutants in Bacillus subtilis by Apparent Nonsense Suppressors. Genetics. 1971 Oct;69(2):133–143. DOI: 10.1093/genetics/69.2.133 PMID: 5002747, PMCID: PMC1212693