They had the following children:

• Agnes (2 Jul 1905, Oss, Netherlands - 14 Feb 1968, Amsterdam, Netherlands)
• Johannes Jacobus (27 Aug 1906, Oss, Netherlands - 18 Oct 1985, Nijmegen, Netherlands)
• Johanna Gertruda (29 Sep 1908, Oss, Netherlands - 8 May 1991, Amsterdam, Netherlands)
• Antoon Frans Hendrik "Toon" (31 Oct 1913, Oss, Netherlands - 15 Jun 1999, Brummen, Netherlands)
• Josefina Emilia Matilda "Fien" (1 Apr 1918, Oss, Netherlands)

Notes:

• Employment: kantoorbediende
• Religion: Roman Catholic
• Family card of Johannes Jacobus Maaskamp from Rotterdam:
• Supporting documents at the wedding:
• The last document is regarding the draft: the draft was established in the Netherlands in 1810, during Napoleon's reign. Until 1898, it was possible to get an exemption by paying a sizable fee to either get another random person drafted, or to get a replacement who took your place in the army. This is what Johannes Jacobus had done, when he was drafted in 1898 (in other words, just in time!). At the time of his wedding, that replacement was still in the army.
• Note: Gertruda Johanna Wolters was born in the train station of Mil, where her father was station master. The station was part of the Noord-Brabantsch-Duitsche Spoorweg-Maatschappij (Dutch), a railroad that connected Boxtel, Netherlands to Wesel, Germany. In 1945 it was partially blown up by the Germans when they retreated from the Netherlands.
• Witnesses at Johannes Jacobus's birth: Maria Visser, 46 years old, midwife, living in Rotterdam & Martinus Brinkman, 34 years old, clerk, living in Rotterdam & Wilhelmus Johannes Pluch, 23 years old, clerk, living in Rotterdam
• Witnesses at Gertruda Johanna's birth: Hendricus van der Linden, 49 years old, kastelein (proprietor of a bar, hotel, or restaurant), living in Mil en Sint Hubert & Rudolf Verstraaten, 30 years old, entrepeneur, living in Mil en Sint Hubert
• Witnesses at the wedding: Abraham de Groot, Gertruda's brother-in-law, 44 years old, baker, living in Oss & Petrus Franciscus Joannes Corbesir, 31 years old, employee of the Staatsspoorwegen (SS), living in Oss & Hermanus Teunissen, 28 years old, office worker, living in Oss & Johannes Willem Franciscus Gabriel Thijssen, 26 years old, office worker, living in Oss
• Witnesses at Gertruda Johanna's death: Antonius Hendrik Reinier Martens, koster (sacristan), 53 years old, living in Nijmegen & Antonie Manuel Oosterdijk, commies ter secretarie, 53 years old, living in Nijmegen
• Witness at Johannes's death: Alphonsus Nihof, 41 years old, bedienaar, living in 's-Gravenhage

Sources:

1. "Netherlands, Zuid-Holland Province, Civil Registration, 1679-1942." Database with images. FamilySearch. http://FamilySearch.org : 14 June 2016. Nationaal Archief, Den Haag (National Archives, The Hague).
2. Oss, archieftoegang 550, 4 oktober 1904, Huwelijksregister Oss 1904, aktenummer 50
3. Digitale Stamboom Den Haag. http://denhaag.digitalestamboom.nl/
4. Mill en Sint Hubert, archieftoegang 50, 25 mei 1879, Geboorteregister Mill en Sint Hubert 1879, aktenummer 33
5. "Netherlands, Gelderland Province Civil Registration, 1800-1952." Database with images. FamilySearch. http://FamilySearch.org : 14 June 2016. Rijksarchief de Gelderland, Arnhem (Gelders Archive, Arnhem).