Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
hanh tai » thanh tai, hang tai, han 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
tai va » thai va, mai va, tri 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 tham thuc va hanh tai 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 tham thuc va hanh tai va thiet.
• Adding a wildcard symbol may retrieve word variants: ((tu sac) or (tu sach)) ky nang cao hoi. hieu van tham thuc va hanh tai va thiet*.