Study and teaching 23 Học tập và giảng dạy 20 History 16 Optics 10 Biography 6 English language 6 Lịch sử 6 more ... Văn học 6 History and criticism 5 Chemistry, Physical and theoretical 4 Chinese language 4 Sources 4 Tiếng Anh 4 Advanced mathematics 3 Chemistry, Organic 3 Econometrics 3 Examinations 3 IELTS 3 Physics 3 Problems, exercises, etc 3 Test of English as a foreign language 3 Vietnamese language 3 Xây dựng 3 Bridges 2 Chinese 2 Classification 2 Communist parties 2 Design and construction 2 Dien Bien Phu, Battle of, Điện Biên Phủ, Việt Nam, 1954 2 Economics 2 less ...