Nwankwo, I W; Nwachukwu, N C; Onwuchekwa, E C; Okamgba, O C; Ugbogu, O C

Okezie Caleb Okamgba, Martin O Ifeanyichukwu, Ayodele O Ilesanmi, Lawrence N Chigbu

Ifeanyichukwu, M O; Okamgba, O C; Amilo, G I; Nwokorie, E A

Hahn, Markus; Okamgba, Stella; Scheler, Peter; Freidel, Klaus; Hoffmann, Gerald; Kraemer, Bernhard; Wallwiener, Diethelm; Krainick-Strobel, Ute