Tutoring in Belgrade is an expensive service, maybe just under 15% of students do have regular tutoring sessions (once or twice weekly). It may be about 10% of students who do take tutoring sessions but only when exams are close.
Students in Serbia firstly learn their lessons in a school, work problems, and if they have any difficulties with their lesson, then they call a tutor to help them out.
That said, we can say that in Belgrade, and rest of Serbia, students have a two-part learning method: a basic lesson given in a classroom, and an extra hour and half (standard tutoring session) with a tutor (called private teacher).
Tutors themselves do not carry any books, but it is expected from students to have all books for a session. You can see that Serbian primary and secondary school students work out most problems on their own.