INTERNATIONAL 801,612 Fifth International Conference Mathematical Population Dynamics, Zakopane, Poland, June 21-26, 1998 / Conf. is supported by Committee for Scientific Research (Poland) and Batory Fundation. International Workshop on Spatially Heterogenous Problems in Ecology and Epidemiology : Mathematical Models vs. Polluted Environment Data, Zakopane , Poland, June 21-26, 1998 /