Tamarkin maintained his close friendship and academic collaboration with Friedmann and by 1908 the two were attending lectures by Steklov on partial differential equations.
Tamarkin pinapanatili ang kanyang close friendship at academic pakikipagtulungan sa Friedmann at sa pamamagitan ng 1908 ang dalawang ay dumadalo sa lektura sa pamamagitan ng Steklov sa bahagyang kaugalian equation.