Okpiliya, F., E. Effiong, I. Eni, and E. Eja. “Mangrove Forest Ecosystem Utilization And Depletion: Implication For Occupational Changes In Calabar South, Nigeria”. European Journal of Sustainable Development, vol. 2, no. 1, Feb. 2013, p. 149, doi:10.14207/ejsd.2013.v2n1p149.