found: Pronk, C. Pronk porselein, c1980 (a.e.)t.p. (Groninger Museum)
found: Intern. direct. of arts, 1979/80(Groninger Museum)
found: Telefoongids Nederl., 1978/79(Museum, Groninger)
found: Africa hoy, c1991:p. 3 (Groningen Museum)
found: Song Dong, 2015:colophon (Song Dong: Life is art, art is life held at the Groninger Museum)
found: Bolten, J. Dutch drawings from the collection of Dr. C. Hofstede de Groot, 1967 (a.e.) t.p. (Groninger Museum voor Stad en Lande)
found: Groninger Museum, via WWW, March 24, 2016(Groninger Museum, Museumeiland 1, 9711 ME Groningen, The Netherlands; email: [email protected])