Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
cao duc » dao duc, cao suc, tao duoc
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
va anh » van anh, va danh, va hanh
anh vi » hanh vi, anh va, anh ve
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat ((sach ky) or (sac ky)) nang xa hoi. hieu van ((cao duc) OR (giao duc)) va anh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach ky) OR (sac ky)) nang xa hoi. hieu van ((cao duc) OR (giao duc)) va anh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat ((sach ky) or (sac ky)) nang xa hoi. hieu van ((cao duc) OR (giao duc)) va anh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: thuat ((sach ky) or (sac ky)) nang xa hoi. hieu van ((cao duc) OR (giao duc)) va anh vi cua tre*.