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
cao hoi » cau hoi, co hoi, cao hoc
day dan » day danh, dao dan, cay dan
tu sach » su sach, te sach, tu cach
va vai » va bai, va van, va dai
va va » va van, va vua, va vat

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 ((va va) OR (va vai)) 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 ((va va) OR (va vai)) thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ky nang cao hoi. hieu van nham thuc day dan ((va va) OR (va vai)) thiet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang cao hoi. hieu van nham thuc day dan ((va va) OR (va vai)) thiet*.