Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh hai » thanh phan, thanh hoa, thanh san
hieu van » hieu va, thien van, lieu va
truc ban » thuc ban, truc dan, truc van
cao tang » cao dang
cua tre » cuu tre, cua triet, dua tren
su sach » so sach, vu sach
van cau » van dau, van hau, van chat
ky tang » ky nang, ky dang, kho tang
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((ky tang) or (cao tang)) xa hoi. hieu van cau truc ban thanh hai ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky tang) OR (cao tang)) xa hoi. hieu van cau truc ban thanh hai ((cua tre) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: su sach ((ky tang) or (cao tang)) xa hoi. hieu van cau truc ban thanh hai ((cua tre) or (cua te))*.