Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
hanh vai » hanh vi, hanh va, hanh tai
tu sach » thu sach, su sach, te sach
cao hoi » cau hoi, co hoi, cao hoc
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
tu sac » tu cac, tu san, tu bac
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 sac) or (tu sach)) ky nang cao hoi. hieu van cham thuc va hanh vai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sac) OR (tu sach)) ky nang cao hoi. hieu van cham thuc va hanh vai va thiet.
• Adding a wildcard symbol may retrieve word variants: ((tu sac) or (tu sach)) ky nang cao hoi. hieu van cham thuc va hanh vai va thiet*.