edited by C.J. van Rijsbergen. edited by G. S. Landsberg. edited by G. van Oortmerssen. edited by M.L. van Beusichem. edited by A. van Cauwenberghe. edited by A. van Itterbeek. edited by I.H. Warren. edited by L. van der Hammen. edited by P. W. J. van Rensburg. Edited by J. T. Bergen.