van der Kruit, Pieter C. (2019). "Appendix A.4: Oort and His Students: a List of Ph.D. Theses". Jan Hendrik Oort. Astrophysics and Space Science Library. Vol. 459. Springer International Publishing. pp. 633–635. doi:10.1007/978-3-030-17801-7. ISBN978-3-030-17800-0. S2CID199240526.
van der Kruit, Pieter C. (2019). "Appendix A.4: Oort and His Students: a List of Ph.D. Theses". Jan Hendrik Oort. Astrophysics and Space Science Library. Vol. 459. Springer International Publishing. pp. 633–635. doi:10.1007/978-3-030-17801-7. ISBN978-3-030-17800-0. S2CID199240526.