Perhaps you should try some spelling variations:
qua cham » qua hai, qua cac, va cham
te sach » toc sach
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
hoc van » hoc dan, hoc vat, hoc phan
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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 ty ((nang ma) or (sang ma)) hoa. hieu qua cham ((hoc van) OR (hoc va)) hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((nang ma) OR (sang ma)) hoa. hieu qua cham ((hoc van) OR (hoc va)) hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((nang ma) or (sang ma)) hoa. hieu qua cham ((hoc van) OR (hoc va)) hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty ((nang ma) or (sang ma)) hoa. hieu qua cham ((hoc van) OR (hoc va)) hanh va cua tre*.