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
danh xa » danh ca, dinh xa, canh xa
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
xac va » tac va, ac va, bac 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)) danh xa hoi. hieu van lam ((xac 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)) danh xa hoi. hieu van lam ((xac 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)) danh xa hoi. hieu van lam ((xac va) or (tuc va)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: so ((sach ky) OR (sac ky)) danh xa hoi. hieu van lam ((xac va) or (tuc va)) hanh vi cua tre*.