Perhaps you should try some spelling variations:
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, ang xa, dang xay
mang xa » lang xa, mang may, dang xay
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
cuu tre » cua tre, cau tren, cau treo
su viet » so viet
ve cac » va cac, vien cac
cac ly » cac ky, cac le, cam ly

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 ty ((xang xa) or (mang xa)) hoi. hieu ve cac ly va hanh vi ((cuu tre) or (su viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((xang xa) OR (mang xa)) hoi. hieu ve cac ly va hanh vi ((cuu tre) OR (su viet)).
• Adding a wildcard symbol may retrieve word variants: su sach ty ((xang xa) or (mang xa)) hoi. hieu ve cac ly va hanh vi ((cuu tre) or (su viet))*.