Perhaps you should try some spelling variations:
sua viet » su viet, cua viet, lua viet
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
nam thuc » nam thuoc, am thuc, nam thu
cam tuc » cam xuc, cam tu, dam thuc
tai sua » dai sua, tai su, tai cua
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
vu sach » vu bach, su sach, vu khach

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 (vu sach)) ky tang xa hoi. hieu va ((cam tuc) OR (nam thuc)) van hanh tai sua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (vu sach)) ky tang xa hoi. hieu va ((cam tuc) OR (nam thuc)) van hanh tai sua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (vu sach)) ky tang xa hoi. hieu va ((cam tuc) OR (nam thuc)) van hanh tai sua viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (vu sach)) ky tang xa hoi. hieu va ((cam tuc) OR (nam thuc)) van hanh tai sua viet*.