by Okamoto, Isao, Sigalo, Friday B.
Published in Publications of the Astronomical Society of Japan (25.12.2006)

by Ekeh, Charles C., Uko, Etim D., Eleluwor, Ejiro F., Sigalo, Friday B.
Published in Pakistan Journal of Geology (01.06.2019)

by Uko, Etim D, Otugo, Vivian N, Sigalo, Friday B, Inyang, Udombakuku E. Udonam
Published in Journal of Atmosphere (2016)