MUKHOPADHYAY, GOUTAM, and JASMINA KHANAM. “Separation of Less Satisfactory Surface Active Antibiotic (Penicillin G) From Dilute Solution Using Foam Separation Method”. Asian Journal of Chemistry, vol. 21, no. 5, Mar. 2010, pp. 3861-8, https://asianpubs.org/index.php/ajchem/article/view/17364.