Perhaps you should try some spelling variations:
sang mai » sang ma, sang tai, lang mai
hanh vai » hanh vi, hanh va, hanh tai
tu sach » thu sach, su sach, te sach
cam duc » cam xuc, cao duc, pham duc
cuu tre » cau tren, cau treo
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cua triet, dua tren

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 ky sang mai hoi. ((hieu ve) or (hieu va)) cam duc va hanh vai ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang mai hoi. ((hieu ve) OR (hieu va)) cam duc va hanh vai ((cuu tre) OR (cua tre))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang mai hoi. ((hieu ve) or (hieu va)) cam duc va hanh vai ((cuu tre) OR (cua tre))*".