When did you last see my mother? : a play in six scenes / Christopher Hampton ; introd. and annotations by Jop Spiekerman and Nora Schadee248 objekten : Leids Academisch Kunstcentrum, 11/10 t/m 17/11 1968, Leiden / [inl.: P. Hoenderdos ; vert.: J.A.A. Spiekerman ... et al.]Methodology : foundations of inference and research in the behavioral sciences / by Adriaan D. de Groot ; [rev. transl. from the Dutch by J.A.A. Spiekerman]Otto Selz : his contribution to psychology / ed. by Nico H. Frijda [and] Adriaan D. de Groot ; [transl. by Jop A. Spiekerman and Christine E. Thirlway]The fall of the house of Usher / Edgar Allan Poe ; a play adaption by Steven Berkoff ; introd. and annot. by Jop Spiekerman, Nora SchadeeSizwe Bansi is dead / Athol Fugard, John Kani, Winston Ntshona ; introd. and ann. by Jop Spiekerman