Perhaps you should try some spelling variations:
hanh hai » thanh hai, nhanh hai, hang hai
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach kem
hai cua » thai cua, dai cua, hoi cua
va hanh » van hanh, va thanh, va danh
cau luc » cau truc, cau phuc
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
sach ty » sach y, sach tu, sach thu
luc va » duc va, tuc va, loc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ky) OR (sach ty)) ((nang xa) or (nang ma)) hoi. hieu van cau luc va hanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) ((nang xa) OR (nang ma)) hoi. hieu van cau luc va hanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach ty)) ((nang xa) or (nang ma)) hoi. hieu van cau luc va hanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach ty)) ((nang xa) or (nang ma)) hoi. hieu van cau luc va hanh hai cua tre*.