Your link points to some math review book by the same author. I believe the author meant the drillbook such as https://issuu.com/normagee/docs/scanavi_sbornik_

Your link points to some math review book by the same author. I believe the author meant the drillbook such as https://issuu.com/normagee/docs/scanavi_sbornik_konkursnih_zadach_1/9 https://issuu.com/normagee/docs/scanavi_sbornik_konkursnih_z....