Perhaps you should try some spelling variations:
sach cam » sach cap, mach cam, sach tham
qua pham » quan pham, quy pham, qua cham
va trinh » van trinh, va tinh, lap trinh
trinh le » trinh ly, thinh le, trinh he
su triet » su tien, ve triet
su sach » so sach, vu sach
tang ma » tang van
su viet » so viet

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach cam ((mang may) OR (tang ma)) hoi. hieu qua pham duc va trinh le ((su triet) OR (su viet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach cam ((mang may) or (tang ma)) hoi. hieu qua pham duc va trinh le ((su triet) OR (su viet))~".
• Adding a wildcard symbol may retrieve word variants: su sach cam ((mang may) or (tang ma)) hoi. hieu qua pham duc va trinh le ((su triet) OR (su viet))*.