In educational contexts, (GDZ) refers to "Ready-to-use Homework Solutions." For students in Belarus and parts of the CIS, the physics textbooks authored by L.A. Isachenkova and Y.D. Leshchinskii are staple resources for grades 7 through 9.
The authors provide a comprehensive suite of learning tools beyond just the main textbook: In educational contexts
The study of light, electricity, and magnetic fields. How to Use GDZ Effectively In educational contexts
Heat phenomena and the behavior of substances. In educational contexts