Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
te sach » toc sach
cao hoi » cau hoi, co hoi, cao hoc
thuc va » thuc vat, thuc dan, thuc day
va dan » ca dan, va dao, va dau
vai va » dai va, hai va, lai 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 cao hoi. hieu van pham thuc va dan ((vai va) or (mai va)) thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (thu sach)) ky nang cao hoi. hieu van pham thuc va dan ((vai va) OR (mai va)) thiet.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (thu sach)) ky nang cao hoi. hieu van pham thuc va dan ((vai va) or (mai va)) thiet*.