Perhaps you should try some spelling variations:
tan thanh » tran thanh, tang thanh, toan thanh
hieu van » hieu va, thien van, lieu va
sach thu » sach thue, sach thieu, sach tham
xach tay » canh tay
hoi chu » hoi chuc
hoi cuu » hoi cua, ho cuu, hoi cau
nam duc » nam duoc, pham duc, nam thuc
nang xa » nang x, lang xa, nang ma

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

• Performing a fuzzy search may retrieve terms with similar spellings: so ((xach tay) or (sach thu)) nang xa hoi. hieu van nam duc tan thanh ((hoi cuu) OR (hoi chu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((xach tay) OR (sach thu)) nang xa hoi. hieu van nam duc tan thanh ((hoi cuu) OR (hoi chu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((xach tay) or (sach thu)) nang xa hoi. hieu van nam duc tan thanh ((hoi cuu) OR (hoi chu)) tre".
• Adding a wildcard symbol may retrieve word variants: so ((xach tay) or (sach thu)) nang xa hoi. hieu van nam duc tan thanh ((hoi cuu) OR (hoi chu)) tre*.