Perhaps you should try some spelling variations:
hai truc » dai truc, hai trac, hang truc
su sach » so sach, vu sach
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, dang xay
vi cua » vai cua, di cua
va hai » van hai, va chai, va khai

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 hai truc ((va hanh) OR (va danh)) 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 hai truc ((va hanh) OR (va danh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((mang xa) or (nang ma)) hoi. hieu va hai truc ((va hanh) OR (va danh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((mang xa) or (nang ma)) hoi. hieu va hai truc ((va hanh) OR (va danh)) vi cua tre*.