All papers in Indagationes Mathematicae are now digitized
The mathematics journal
Indagationes Mathematicae is owned by the
Koninklijk Wiskundig Genootschap (KWG), and it is published by
Elsevier. The journal originates from the Proceedings of the
Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) Series A.
Recently Elsevier has digitized the volumes which appeared during 19511968.
This filled the last gap in the digitization of the back issues of
Indag. Math and Proc. KNAW (Ser. A). They are now available as follows:
The first two mentioned sites have open access.
On the third site all papers which have appeared more than 48 months ago
have open access.
Here are a few examples of important papers which appeared in
Indag. Math in the period 19511968 and which are now digitized:

N.G. de Bruijn,
Generalization of Polya’s fundamental theorem in enumerative combinatorial
analysis,
Indag. Math. (1959), 5969.

A.H.M. Levelt,
Hypergeometric functions, I, II, III, IV,
Indag. Math. (1961), 361403.

J. Tits,
Une classe d'algèbres de Lie en relation avec les algèbres de Jordan,
Indag. Math. (1962), 530535.

J.H. van Lint and J.J. Seidel,
Equilateral point sets in elliptic geometry,
Indag. Math. (1966), 335348.

J.N. Mather,
Characterization of Anosov diffeomorphisms,
Indag. Math. (1968), 479483.
Read about the history of Indagationes Mathematicae the following paper
(in Dutch):
J. Korevaar and R. Tijdeman,
De geschiedenis van Indagationes Mathematicae,
Nieuw Arch. Wisk. (5) 14 (2013), 6672.
Note that during 19391979 KNAW published the two journals
Proc. KNAW Ser. A and Indag. Math. which were completely identical, except
that one should subtract 41 from the volume number of
Proc. KNAW Ser. A in order to obtain the volume number of Indag. Math.
On
ScienceDirect Indagationes Mathematicae (Proceedings)
Elsevier uses the volume numbers of Proc. KNAW Ser. A.
Starting in 1990, only Indag. Math. was published. The volume number started
with 1 again in 1990. For proper citation one should add N.S. (New Series).
to Tom Koornwinder's home page