Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
tham xuc » tham nuoc, pham duc, cam xuc
van hanh » van thanh, ban hanh, van anh
hanh ki » hanh vi, hanh ky, hanh kien
sach tu » sach thu, cach tu, sach ty
tu sach » thu sach, su sach, te sach
tu nang » tru nang, tu nong, tu nano
su viet » so viet
ma hoi » mai hoi, ma hoa, me hoi
ki su » ky su

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 tu nang ((ma hoi) OR (xa hoi)). hieu qua ((tham xuc) or (tham thuc)) van hanh ki su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu nang ((ma hoi) OR (xa hoi)). hieu qua ((tham xuc) OR (tham thuc)) van hanh ki su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu nang ((ma hoi) OR (xa hoi)). hieu qua ((tham xuc) or (tham thuc)) van hanh ki su viet".
• Adding a wildcard symbol may retrieve word variants: tu sach tu nang ((ma hoi) OR (xa hoi)). hieu qua ((tham xuc) or (tham thuc)) van hanh ki su viet*.