Perhaps you should try some spelling variations:
thanh dong » thanh duong, thanh cong, hanh dong
dam thanh » dao thanh, nam thanh, am thanh
dong cua » dung cua, cong cua, huong cua
thuc dam » thuc dan, thuc day, thuc pham
nam thuc » nam thuoc, am thuc, nam thu
hieu van » thien van, lieu va, hieu ve
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach kem
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, sach thu

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 ky) OR (sach ty)) nang xa hoi. ((hieu van) or (hieu va)) nam thuc dam thanh dong cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ky) OR (sach ty)) nang xa hoi. ((hieu van) OR (hieu va)) nam thuc dam thanh dong cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach ky) OR (sach ty)) nang xa hoi. ((hieu van) or (hieu va)) nam thuc dam thanh dong cua tre".
• Adding a wildcard symbol may retrieve word variants: toc ((sach ky) OR (sach ty)) nang xa hoi. ((hieu van) or (hieu va)) nam thuc dam thanh dong cua tre*.