Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
kho tang » cao tang
danh vu » danh tu, anh vu, danh du
va danh » va dinh, va dan, va hanh
cau hoc » cau hoi, cau hoa, cao hoc
cau loc » hau loc, cau luc, cau long
su sach » so sach, vu sach
ky tang » ky nang, ky dang, ky trong
vu va » vu van, tu va, su va

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 ((ky tang) OR (kho tang)) xa hoi. hieu qua ((cau loc) OR (cau hoc)) va danh vu va trien~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky tang) or (kho tang)) xa hoi. hieu qua ((cau loc) OR (cau hoc)) va danh vu va trien~".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky tang) or (kho tang)) xa hoi. hieu qua ((cau loc) OR (cau hoc)) va danh vu va trien*.