Perhaps you should try some spelling variations:
sua viet » cua viet, lua viet, qua viet
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
cam tuc » cam xuc, cam tu, nam thuc
tuc van » thuc van, truc van, tuc va
su viet » so viet
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
va cam » va cham, va cac, va cao

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 van hanh tai ((sua viet) OR (su 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 van hanh tai ((sua viet) OR (su 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 van hanh tai ((sua viet) OR (su viet))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (vu sach)) ky tang xa hoi. hieu va cam tuc van hanh tai ((sua viet) OR (su viet))*.