References:
Whitt DD, Carlton BC. Characterization of mutants with single and multiple defects in the tryptophan biosynthetic pathway in Bacillus subtilis. Journal of Bacteriology. 1968 Oct;96(4):1273-1280. DOI: 10.1128/jb.96.4.1273-1280.1968 PMID: 4971887, PMCID: PMC252444
Whitt DD, Carlton BC. Non-coordinate regulation in 5-methyl tryptophan-resistant mutants of Bacillus subtilis. Biochemical and Biophysical Research Communications. 1968 Nov 25;33(4):636-642. DOI: 10.1016/0006-291x(68)90343-4 PMID: 4972288