Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
thu sach » thuat sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
van nham » van nam, van nhan, van tham
thuc day » thuc dan, thuc vat
tu sach » su sach, te sach, tu cach
cao hoi » cau hoi, co hoi, cao hoc
day dan » day danh, dao dan, cay dan
dan vai » dan va, dan tai, dan vat
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: ((tu sach) or (thu sach)) ky nang cao hoi. hieu van nham thuc day dan vai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang cao hoi. hieu van nham thuc day dan vai va thiet.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang cao hoi. hieu van nham thuc day dan vai va thiet*.