Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
van thanh » ban thanh, van tuan
nam thuc » nam thuoc, am thuc, nam thu
tu sach » thu sach, su sach, te sach
cam tuc » cam xuc, cam tu, dam thuc
tai cuu » tai cuc, tai buu, tai cua
cuu tre » cua tre, cau tren, cau treo
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao

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 ty ((nang ma) or (nang x)) hoi. hieu va ((cam tuc) OR (nam thuc)) van thanh tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang ma) OR (nang x)) hoi. hieu va ((cam tuc) OR (nam thuc)) van thanh tai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang ma) or (nang x)) hoi. hieu va ((cam tuc) OR (nam thuc)) van thanh tai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang ma) or (nang x)) hoi. hieu va ((cam tuc) OR (nam thuc)) van thanh tai cuu tre*.