Perhaps you should try some spelling variations:
danh vai » danh sai, danh va, doanh van
cam truc » cau truc, nam truc, lam truoc
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, te sach, tu cach
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
truc va » thuc va, thuc vat, trung va
van cam » van nam, van lam, van cau
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
su sach » so sach, vu sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) OR (su sach)) thu ((nang xa) or (nang ma)) hoi. hieu van cam truc va danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) thu ((nang xa) OR (nang ma)) hoi. hieu van cam truc va danh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (su sach)) thu ((nang xa) or (nang ma)) hoi. hieu van cam truc va danh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (su sach)) thu ((nang xa) or (nang ma)) hoi. hieu van cam truc va danh vai cua tre*.