Louis Koster was married to Sara de Zwarte. On 18 November 1942 their son Meijer was born in camp Westerbork.
Birth certificate register, which was drafted by the auxiliary administrative office of the civil registration in camp Westerbork; Westerbork archives, which are now part of the archives of Midden-Drenthe in Beilen
In addition, a Jokos file (number 50775) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.