Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
vat thanh » dat thanh, gat thanh, tat thanh
nang van » dang van, tang van, lang van
nam thuc » nam thuoc, nam thu, nam tu
tu sach » thu sach, su sach, tu cach
te sach » toc sach
van hoc » van hoa
dat cua » dai cua, day cua, mat cua
cua tre » cua te, cuu tre, cua triet

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 (te sach)) ky nang van hoc. hieu qua ((nam thuc) OR (am thuc)) vat thanh dat cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang van hoc. hieu qua ((nam thuc) OR (am thuc)) vat thanh dat cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ky nang van hoc. hieu qua ((nam thuc) OR (am thuc)) vat thanh dat cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky nang van hoc. hieu qua ((nam thuc) OR (am thuc)) vat thanh dat cua tre*.