All papers in Indagationes Mathematicae are now digitized, Tom Koornwinder, June 3, 2015, accessed 2017-01-20. https://staff.fnwi.uva.nl/t.h.koornwinder/dutchmathjournals/IndagMath.html
Korevaar, J.; Tijdeman, R. (2013), "De geschiedenis van Indagationes Mathematicae" (PDF), Nieuw Archief voor Wiskunde, 5th Ser. (in Dutch), 14: 66–72. /wiki/Jacob_Korevaar
Broer, Henk W. (2019), "Indagationes Mathematicae 2009--2018" (PDF), Nieuw Archief voor Wiskunde, 5th Ser. (in Dutch), 20: 9–10. /wiki/Henk_Broer
Reed Elsevier Timeline Archived 2015-10-30 at the Wayback Machine, University Library, Northern Illinois University, accessed 2017-01-20. https://www.ulib.niu.edu/publishers/ReedElsevier.htm
All papers in Indagationes Mathematicae are now digitized, Tom Koornwinder, June 3, 2015, accessed 2017-01-20. https://staff.fnwi.uva.nl/t.h.koornwinder/dutchmathjournals/IndagMath.html
Korevaar, J.; Tijdeman, R. (2013), "De geschiedenis van Indagationes Mathematicae" (PDF), Nieuw Archief voor Wiskunde, 5th Ser. (in Dutch), 14: 66–72. /wiki/Jacob_Korevaar
Knuth, Donald E. (1996), "Questions and Answers II" (PDF), TUGboat, 17: 355–367. Reprinted as chapter 32 of Digital Typography, pp. 601–624. See especially p. 364 (p. 620): "And the third source was a copy of Indagationes Mathematicae, the Dutch journal. There's a long fine tradition of quality printing in the Netherlands, and I selected an issue from 1950 or thereabouts, where again I thought that the mathematics was particularly well done." /wiki/Donald_Knuth