Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
sach vu » sach va, sach tu, sach uu
vu nang » vuc nang, va nang, vu dang
nang ma » tang ma, sang ma, nang cao
van cam » van nam, van lam, van cau
truc va » thuc va, trung va
ma hoi » mai hoi, xa hoi, ma hoa
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: so sach vu nang ma hoi. hieu van cam ((truc va) or (thuc vat)) thanh dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach vu nang ma hoi. hieu van cam ((truc va) OR (thuc vat)) thanh dai cua te.
• Adding a wildcard symbol may retrieve word variants: so sach vu nang ma hoi. hieu van cam ((truc va) or (thuc vat)) thanh dai cua te*.