Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
lai cua » dai cua, hai cua, lai chau
va hanh » va thanh, va danh, ban hanh
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
sach tu » sach thu, cach tu, sach ty
cam lo » nam lo, cam ly, cam o
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: te ((sach y) or (sach tu)) nang ma hoa. hieu va cam lo ((va hanh) OR (van hanh)) lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach y) OR (sach tu)) nang ma hoa. hieu va cam lo ((va hanh) OR (van hanh)) lai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach y) or (sach tu)) nang ma hoa. hieu va cam lo ((va hanh) OR (van hanh)) lai cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach y) or (sach tu)) nang ma hoa. hieu va cam lo ((va hanh) OR (van hanh)) lai cua tre*.