Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, van thanh
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
sach thu » sach thue, sach thieu, sach tham
nam thuc » nam thuoc, am thuc, nam thu
sach ty » sach y, sach tu, xach tay
nang xa » nang x, lang xa, nang ma
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: su ((sach ty) OR (sach thu)) nang xa hoi. hieu van nam thuc ((dan thanh) or (ban thanh)) de cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) nang xa hoi. hieu van nam thuc ((dan thanh) OR (ban thanh)) de cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach thu)) nang xa hoi. hieu van nam thuc ((dan thanh) or (ban thanh)) de cua te".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach thu)) nang xa hoi. hieu van nam thuc ((dan thanh) or (ban thanh)) de cua te*.