Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
than thuc » thuan thuc, nhan thuc, toan thuc
toc sach » hoc sach, doc sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
hieu va » lieu va, hieu qua
va than » va thanh, van than, va phan
nang co » nang cao, nang doc, nang noi
so sach » so sanh, bo sach, co sach
co hoi » co hoc, co loi
di cua » dai cua, doi cua, de cua
di ca » di cau, doi ca, li ca

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (so sach)) ky nang co hoi. hieu va than thuc dan thanh ((di ca) OR (di cua)) tra~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (so sach)) ky nang co hoi. hieu va than thuc dan thanh ((di ca) OR (di cua)) tra.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (so sach)) ky nang co hoi. hieu va than thuc dan thanh ((di ca) OR (di cua)) tra".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (so sach)) ky nang co hoi. hieu va than thuc dan thanh ((di ca) OR (di cua)) tra*.