Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
sang ma » tang ma, nang ma, sang tao
cam tuc » cam xuc, cam tu, nam thuc
va cam » va cham, va cac, va cao
de su » den su, ve su, de tu

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 y ((sang ma) or (mang may)) hoi. hieu va cam tuc ((va hanh) OR (va danh)) de su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((sang ma) OR (mang may)) hoi. hieu va cam tuc ((va hanh) OR (va danh)) de su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((sang ma) or (mang may)) hoi. hieu va cam tuc ((va hanh) OR (va danh)) de su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((sang ma) or (mang may)) hoi. hieu va cam tuc ((va hanh) OR (va danh)) de su triet*.