Santos, M.C.F.V., J.C. Zieman, and R.R.H. Cohen. 1997. Interpreting the upper mid-littoral zonation patterns of Maranhao state mangals, northern Brazil, as a response to microtopography and local hydrology. In: B.J. Kjerfve, L.D. de Lacerda and E. H. S. Diop, eds: Mangrove Ecosystem Studies in Latin America and Africa. pp. 127-144. UNESCO, Paris, publishers