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

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) OR (nam thuc)) tan thanh hoi cuu 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) OR (nam thuc)) tan thanh hoi cuu 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) OR (nam thuc)) tan thanh hoi cuu tre".
• Adding a wildcard symbol may retrieve word variants: so ((xach tay) or (sach thu)) nang xa hoi. hieu van ((nam duc) OR (nam thuc)) tan thanh hoi cuu tre*.