Perhaps you should try some spelling variations:
dua tren » dung tren
cuu tre » cua tre, cau tren, cau treo
hanh ca » hanh cac, hanh cat, hanh cua
va hanh » van hanh, va thanh, va danh
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
mai hoi » mai khoi, dai hoi, lai hoi
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
cac tuc » cac toc, cac tu, cac tac
tuc va » thuc va, truc va, tuc xa

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 lang) or (ky tang)) mai hoi. hieu va cac tuc va hanh ca ((cuu tre) or (dua tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky lang) OR (ky tang)) mai hoi. hieu va cac tuc va hanh ca ((cuu tre) OR (dua tren)).
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) or (ky tang)) mai hoi. hieu va cac tuc va hanh ca ((cuu tre) or (dua tren))*.