Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
hieu va » lieu va
cac tuc » cac toc, cac tu, cac tac
va vanh » va van, va danh, va hanh
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
tuc va » thuc va, truc va, tuc xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) OR (sac ky)) nang xa hoi. ((hieu va) or (hieu qua)) cac tuc va vanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sac ky)) nang xa hoi. ((hieu va) OR (hieu qua)) cac tuc va vanh dai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) OR (sac ky)) nang xa hoi. ((hieu va) or (hieu qua)) cac tuc va vanh dai cua tre*".