Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
sach ky » sach y, sach ty, sach kem
van lam » van nam
dang xa » dang xay, lang xa, dang ha
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
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: so ((sach ky) OR (sac ky)) dang xa hoi. hieu van lam ((xuc va) or (tuc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ky) OR (sac ky)) dang xa hoi. hieu van lam ((xuc va) OR (tuc va)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach ky) OR (sac ky)) dang xa hoi. hieu van lam ((xuc va) or (tuc va)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: so ((sach ky) OR (sac ky)) dang xa hoi. hieu van lam ((xuc va) or (tuc va)) hanh vi cua tre*.