Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
van hanh » van thanh, ban hanh, van anh
sang mai » sang ma, sang tai, lang mai
mai khoi » mai khoa, tai khoa, cac khoi
sach ky » sac ky, sach y, sach ty
cam tuc » cam tu, nam thuc, dam thuc
tu sach » thu sach, su sach, te sach
ky sang » ky nang, ky dang, ky tang
hieu ve » hieu van
hieu va » lieu va, hieu qua
vi cau » va cau, ve cau, di cau

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 khoi. ((hieu ve) or (hieu va)) ((cam tuc) OR (cam xuc)) van hanh vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang mai khoi. ((hieu ve) OR (hieu va)) ((cam tuc) OR (cam xuc)) van hanh vi cau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang mai khoi. ((hieu ve) or (hieu va)) ((cam tuc) OR (cam xuc)) van hanh vi cau tren*".