Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
sach tu » sach thu, cach tu, sach ty
hieu va » lieu va, hieu qua
cac vuc » cac nuoc, cac vung, cac cuoc
vuc van » duc van, luc van, thuc van
van anh » van thanh, tuan anh, van minh
anh dai » vanh dai, anh bai, anh dat
cua tu » cua tuc, cua cu, cua te
cua su » qua su

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach tu ((nang ma) or (sang ma)) hoi. hieu va cac vuc van anh dai ((cua tu) or (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach tu ((nang ma) OR (sang ma)) hoi. hieu va cac vuc van anh dai ((cua tu) OR (cua su)).
• Adding a wildcard symbol may retrieve word variants: hoc sach tu ((nang ma) or (sang ma)) hoi. hieu va cac vuc van anh dai ((cua tu) or (cua su))*.