Perhaps you should try some spelling variations:
khai truc » khai thac, dai truc, hai trac
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
mang xa » lang xa, mang may, dang xay
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
va khai » van khai, va khao, va kha
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
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: su sach ky ((mang xa) or (nang ma)) hoi. hieu va khai truc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((mang xa) OR (nang ma)) hoi. hieu va khai truc va hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ky ((mang xa) or (nang ma)) hoi. hieu va khai truc va hanh vi cua tre*.