Srivastava, U.S. and Srivastava, P.D. (1956) “On the Hydrogen-Ion Concentration in the Alimentary Canal of Certain Orthopteroid Insects”., Contributions to Entomology = Beiträge zur Entomologie, 6(5-6), pp. 493–498. doi:10.21248/contrib.entomol.6.5-6.493-498.