Image Algemeen Handelsblad 26 februari 1934, pag. 4. Leopold Smit, harpconcert in A'dam. By: on 9 January 2012 Image Algemeen Handelsblad 5 september 1931, avond, pag. 8. Adv. school Els Keezer en Ruth Tobi. By: on 10 October 2012
Image Algemeen Handelsblad 26 februari 1934, pag. 4. Leopold Smit, harpconcert in A'dam. By: on 9 January 2012
Image Algemeen Handelsblad 5 september 1931, avond, pag. 8. Adv. school Els Keezer en Ruth Tobi. By: on 10 October 2012
