Perhaps you should try some spelling variations:
dinh hai » dinh thai, tinh hai, dinh ha
hai cua » thai cua, dai cua, hoi cua
sach ky » sac ky, sach ty, sach kem
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
lop va » lap va, hop va
nop va » hop va
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) or (sach y)) nang x hoi. hieu va cac ((lop va) OR (nop va)) dinh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sach y)) nang x hoi. hieu va cac ((lop va) OR (nop va)) dinh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) or (sach y)) nang x hoi. hieu va cac ((lop va) OR (nop va)) dinh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sach y)) nang x hoi. hieu va cac ((lop va) OR (nop va)) dinh hai cua tre*.