Three letters and two articles are included in the K. Groot’s study of the connections between Kohlbrugge and Kuyper. The first letter (pp. 100–101) was sent to H.F. Kohlbrugge from Amsterdam on December 22, 1870. Sent as a cover letter with 1870.31, it contains several questions (for example, whether Ed. Böhl or J. Künzli might be willing to contribute articles to De Heraut). The second letter (p. 103) is undated but was likely written shortly after the previous letter. It is addressed to Mrs. P. Boissevain-Drost, the wife of Kohlbrugge’s friend in Amsterdam, H.J.A. Boissevain (1813–1891). The third letter (p. 147) was sent to the Rev. H.A.J. Lütge (1850–1923) on January 24, 1887 (though it is mistakenly dated 1886). Lütge was among the followers of Kohlbrugge who did not support Kuyper’s efforts toward church reform; Kuyper therefore returned a portrait of Kohlbrugge that Lütge had given to him along with this short letter of explanation (see also 1987.05).

Two articles are also included in this volume. The first is a memorial for Kohlbrugge (†March 5, 1875), which is reprinted (pp. 124–126) from the Zondagsblad van De Standaard 4 (1875), no. 50, March 14, 1875. The article is dated Amsterdam, March 10, 1875. The second (pp. 135–136) is an editorial from De Heraut, no. 152, November 21, 1880, in which Kuyper explains his reservations about the judgment that L.H. Wagenaar (1855–1910) had put forward about Kohlbrugge in his dissertation Het “Réveil” en de “Afscheiding” (Heerenveen, 1880).