Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
thanh de » hanh de, thanh ve, thanh do
tu sach » thu sach, su sach, te sach
cau hoc » cau hoi, cau hoa, cao hoc
hieu va » hieu qua
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
de cua » le cua, te cua, dieu cua
cua te » cua 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 ((nang xa) or (nang ma)) hoi. ((hieu va) or (lieu va)) cau hoc dan thanh de cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang xa) OR (nang ma)) hoi. ((hieu va) OR (lieu va)) cau hoc dan thanh de cua te.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang xa) or (nang ma)) hoi. ((hieu va) or (lieu va)) cau hoc dan thanh de cua te*.