Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
hieu van » thien van, lieu va, hieu ve
thu sach » tu sach, thuat sach, thuoc sach
hieu va » lieu va, hieu qua
dan vai » dan va, dan tai, dan vat
thuc ca » thuc cua, thuc can, thuc cao
te sach » toc sach
nang co » nang cao, nang doc, nang noi
co hoi » co hoc, co loi
ca dan » cac dan, ca dao
vai va » mai va, dai va, hai va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (thu sach)) ky nang co hoi. ((hieu van) or (hieu va)) pham thuc ca dan vai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (thu sach)) ky nang co hoi. ((hieu van) OR (hieu va)) pham thuc ca dan vai va thiet.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (thu sach)) ky nang co hoi. ((hieu van) or (hieu va)) pham thuc ca dan vai va thiet*.