Kungsanan, S., S. Kittisrisawai, B. Kitiyanan, T. Rirksomboon, S. Osuwan, and J. F. Scamehorn. “Recovery of Alcohol Ethoxylates Nonionic Surfactant Using Co-Current Vacuum Stripping”. ASEAN Journal of Chemical Engineering, Vol. 11, no. 1, Dec. 2011, pp. 22-27, https://dev.journal.ugm.ac.id/v3/AJChE/article/view/8077.