Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
cham tuc » nham thuc, pham thuc, cham soc
hanh vai » hanh vi, hanh va, hanh tai
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
va hanh » van hanh, va thanh, va danh
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
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 ve ((cham tuc) or (tham thuc)) va hanh 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 ve ((cham tuc) OR (tham thuc)) va hanh vai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ky nang cao hoi. hieu ve ((cham tuc) or (tham thuc)) va hanh vai va thiet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) ky nang cao hoi. hieu ve ((cham tuc) or (tham thuc)) va hanh vai va thiet*.