EL-OWAIDY, H., AMMAR, A.A. and EL-LEITHY, O.A. 1990. COMPETITION IN THE GRADOSTAT FOR THE CASE OF THREE VESSELS AND THREE POPULATIONS. Tamkang Journal of Mathematics. 21, 2 (Jun. 1990), 143–158. DOI:https://doi.org/10.5556/j.tkjm.21.1990.4650.