Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
thanh doi » thanh loi, thanh moi, thanh do
sach kem » hanh kem
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
cua viet » ca viet, hoa viet, cua vat
sach ky » sach y, sach ty, sach hay
nang xa » nang x, lang xa, nang ma
doi cua » dai cua, hoi cua
sac ky » cac ky, sai ky

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