Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hai truc » dai truc, hai trac, hang truc
sach ky » sac ky, sach ty, sach kem
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
van hai » van ha, van chat, van hanh
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
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: vu ((sach ky) OR (sach y)) ((mang xa) or (nang ma)) hoi. hieu van hai truc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sach ky) OR (sach y)) ((mang xa) OR (nang ma)) hoi. hieu van hai truc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sach ky) OR (sach y)) ((mang xa) or (nang ma)) hoi. hieu van hai truc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: vu ((sach ky) OR (sach y)) ((mang xa) or (nang ma)) hoi. hieu van hai truc va hanh vi cua tre*.