[4] Hounslow M W,Morton A C.Sedimentary Geology,2004,171(1-4):13.
[5] Ubangoh R U,Pacca I G,Nyobe J B,et al.Journal of Volcanology of Cameroon Research,2005,142(3-4):225.
[6] Diana J,Neli J,Bernard H,et al.Eearth and Planetary Science Letters,2007,255:390.