Saranya Phunpruch and Kei Kamino, “Study on the Acyl-Homoserine Lactone Production of a Gram-Negative Bacterium Sphingomonas xenophaga by Co-Cultivation with Variovorax paradoxus”, Agr. Nat. Resour., vol. 38, no. 5, pp. 21–28, Oct. 2004.