Seki Y, Ikeda S, Kiyohara H, Ayabe H, Seki T, Matsui H (May 2002). "Sequencing analysis of a putative human O-sialoglycoprotein endopeptidase gene (OSGEP) and analysis of a bidirectional promoter between the OSGEP and APEX genes". Gene. 285 (1–2): 101–8. doi:10.1016/S0378-1119(02)00429-8. PMID12039036.
Seki Y, Ikeda S, Kiyohara H, Ayabe H, Seki T, Matsui H (May 2002). "Sequencing analysis of a putative human O-sialoglycoprotein endopeptidase gene (OSGEP) and analysis of a bidirectional promoter between the OSGEP and APEX genes". Gene. 285 (1–2): 101–8. doi:10.1016/S0378-1119(02)00429-8. PMID12039036.