Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
sach thu » sach thue, sach thieu, sach tham
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach ty
lang ha » long ha
cua tre » cua te, cuu tre, cua triet
ha hoi » hoa hoi, ha noi, xa hoi
vi cua » vai cua, di cua
ac va » tac va, bac va, mac va

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 (sach thu)) lang ha hoi. hieu van dao ((ac va) or (thuc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach ky) OR (sach thu)) lang ha hoi. hieu van dao ((ac va) OR (thuc va)) hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: so ((sach ky) or (sach thu)) lang ha hoi. hieu van dao ((ac va) or (thuc va)) hanh vi cua tre*.