Joel Baars was a son of Hartog Baars (who passed away in August 1935) and Rebecca Brilleman. He married in Amsterdam on 16 April 1942 to Martha Annetta Kleerekoper, daughter of Isaac Naphtalie Kleerekoper and Rachel Philippina Horneman.
City Archive of Amsterdam, archive card of Rebecca Brilleman.
In addition, a Jokos file (number 55586) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.