Inspiring. Anyone know any problem-books that could match the (implied) breadth of the one indicated? "I went back to the library and found the mathematics bo

Inspiring. Anyone know any problem-books that could match the (implied) breadth of the one indicated? "I went back to the library and found the mathematics book with the largest number of problems. The book was in Russian, and I didn’t know Russian, but a young linguist is not afraid to pick up another language."