Perhaps you should try some spelling variations:
sach ky » sac ky, sach ty, sach kem
hai cua » thai cua, dai cua, hoi cua
dan hai » doan hai, dang hai, dan khai
cac lop » cac hop, cac loai
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
nang xa » lang xa, nang ma, mang xa
lop va » lap va, hop va, nop va
va dan » ca dan, va dao, va dau

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 xa) or (nang x)) hoi. hieu va cac lop va dan hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sach y)) ((nang xa) OR (nang x)) hoi. hieu va cac lop va dan hai cua tre.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sach y)) ((nang xa) or (nang x)) hoi. hieu va cac lop va dan hai cua tre*.