Jacob Magnus was a member of the Achilles football association in Assen. His name appears with those of seven other Jewish club members killed during World War II on a monument at the sports complex of this association on the Marsdijk.
H. Hamburger and J.C. Regtien, Joodse oorlogsmonumenten in de provincie Drenthe. Profiel (Bedum 1999) 11
For more information and a photo see:
F.J. Hulst en H.M. Luning, De Joodse gemeente Assen, Geschiedenis van een behoorlijke kille, 1740-1976, Asser Historische Reeks III (Assen 1991) p. 126
This person is commemorated on a memorial in Assen. More information on this memorial can be found (in Dutch) on the website of the Nationaal Comité 4 en 5 mei.