Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
cac tuc » cac toc, cac tu, cac tac
tuc ban » thuc ban, truc ban, tu ban
hang vi » hang va, hanh vi, khang voi
hang di » hang doi, hang dien, hang dich
cua tre » cua te, cuu tre, cua triet

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

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