Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
va doanh » van doanh, vay doanh, va danh
hieu van » hieu va, thien van, lieu va
tu sach » su sach, te sach, tu cach
tai cua » thai cua, tai cuc, tri cua
van cho » van chi, san cho, van chat
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
cho xu » chao xu, choi xu, cho xa
xu va » xu van, tu va, su va

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 (thu sach)) ty ((nang ma) or (nang x)) hoi. hieu van cho xu va doanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty ((nang ma) OR (nang x)) hoi. hieu van cho xu va doanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty ((nang ma) or (nang x)) hoi. hieu van cho xu va doanh tai cua tre*.