Perhaps you should try some spelling variations:
nang dai » nang dau, nang tai, lang dai
van hanh » van thanh, ban hanh, van anh
so sach » so sanh, bo sach, co sach
cam tuc » cam xuc, cam tu, nam thuc
dao cua » dai cua, day cua, dan cua
va hanh » va thanh, va danh, ban hanh
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
dai hoa » dai khoa, dai hoc, dai hoi
cua tre » cua te, cuu tre, cua triet

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky nang dai hoa. ((hieu ve) or (hieu qua)) cam tuc ((va hanh) OR (van hanh)) dao cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang dai hoa. ((hieu ve) OR (hieu qua)) cam tuc ((va hanh) OR (van hanh)) dao cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang dai hoa. ((hieu ve) or (hieu qua)) cam tuc ((va hanh) OR (van hanh)) dao cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang dai hoa. ((hieu ve) or (hieu qua)) cam tuc ((va hanh) OR (van hanh)) dao cua tre*.