Smotri v korenʹ! : sbornik l︠i︡ubopytnykh zadach i voprosov - Makove︠t︡skiĭ, P. V. (Petr Vasilʹevich) (Izd-vo "Nauka," Glav. red. fiziko-matematicheskoĭ lit-ry, 1968)