Sergei Aleksandrovich Rachinskii
1001 задача для умственного счета
Sergei Aleksandrovich Rachinskii · 2005
Public domain, Project Gutenberg. No sign-up.
Word problems (Mathematics)Mathematics -- Problems, exercises, etc.
Sergei Aleksandrovich Rachinskii · 2005
Public domain, Project Gutenberg. No sign-up.