^Oka S, Nakajima K, Yamashita A, Kishimoto S, Sugiura T (novembar 2007). "Identification of GPR55 as a lysophosphatidylinositol receptor". Biochemical and Biophysical Research Communications. 362 (4): 928–34. doi:10.1016/j.bbrc.2007.08.078. PMID17765871.
^Oka S, Toshida T, Maruyama K, Nakajima K, Yamashita A, Sugiura T (januar 2009). "2-Arachidonoyl-sn-glycero-3-phosphoinositol: a possible natural ligand for GPR55". Journal of Biochemistry. 145 (1): 13–20. doi:10.1093/jb/mvn136. PMID18845565.