Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
sua viet » su viet, cua viet, qua viet
hanh tai » thanh tai, hang tai, han tai
lua viet » luat viet, luan viet, cua viet
dai hoi » dai hoc, dai hai, dai moi
mai hoi » mai khoi, lai hoi, mai doi
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
cam tuc » cam xuc, cam tu, nam thuc
va hanh » van hanh, va thanh, va danh
ky tang » ky nang, ky dang, kho tang
tuc va » thuc va, truc va, tuc xa
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: thu sach ky tang ((mai hoi) OR (dai hoi)). hieu va cam tuc va hanh tai ((sua viet) or (lua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky tang ((mai hoi) OR (dai hoi)). hieu va cam tuc va hanh tai ((sua viet) OR (lua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky tang ((mai hoi) OR (dai hoi)). hieu va cam tuc va hanh tai ((sua viet) or (lua viet))".
• Adding a wildcard symbol may retrieve word variants: thu sach ky tang ((mai hoi) OR (dai hoi)). hieu va cam tuc va hanh tai ((sua viet) or (lua viet))*.