In August 1941 Hartog de Bruin was enrolled in the second year of the programme for electricians of the 3rd vocational school in East Amsterdam.
Data on Jewish students at Amsterdam vocational schools in 1941Lists of Jewish students at vocational schools in Amsterdam appear in: A. Caransa, Van School Verwijderd. Jood. Dokumenten betreffende de verwijdering van joodse leerlingen van Amsterdamse ambachtsscholen in 1941 (Tuindorp z.d.).