Perhaps you should try some spelling variations:
sach thue » sach thu, sach thieu, sach tham
thue nang » thien nang, thuat nang, thi nang
dat thanh » dao thanh, dat khanh, dang thanh
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, nam thu, nam tu
nang xa » nang x, lang xa, nang ma
do cua » doi cua, de cua, dong cua
co cua » con cua, ca cua, cong cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach thue nang xa hoi. hieu van ((nam thuc) or (am thuc)) dat thanh ((do cua) OR (co cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thue nang xa hoi. hieu van ((nam thuc) OR (am thuc)) dat thanh ((do cua) OR (co cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach thue nang xa hoi. hieu van ((nam thuc) or (am thuc)) dat thanh ((do cua) OR (co cua)) tre".
• Adding a wildcard symbol may retrieve word variants: toc sach thue nang xa hoi. hieu van ((nam thuc) or (am thuc)) dat thanh ((do cua) OR (co cua)) tre*.