On the core of a collection of coalitions / J.J.M. Derks, J.H. ReijnierseVoluntary contribution to multiple public projects / by M. Koster, H. Reijnierse and M. VoorneveldVoluntary contribution to multiple public projects / by M. Koster, H. Reijnierse and M. VoorneveldA dual description of the class of games with a population monotonic allocation scheme / by Henk Norde and Hans ReijnierseFinite coverings by cones / by Stef Tijs and Hans ReijnierseCongestion network problems and related games / by M. Quant, P.E.M. Borm, J.H. ReijniersePublic congestion network situations, and related games / by John Kleppe, Hans Reijnierse