Perhaps you should try some spelling variations:
sach thu » sach thue, sach tham, cach thuc
hanh dai » hanh tai, hanh dao, vanh dai
cua viet » ca viet, hoa viet, cua vat
mang xa » lang xa, mang may, dang xay
va hanh » van hanh, va thanh, va danh
hieu y » hieu ky, hieu ly, hiem y
y pham » my pham, d pham, v pham

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach thu) OR (sach thieu)) ((mang xa) or (nang x)) hoi. hieu y pham duc va hanh dai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach thu) OR (sach thieu)) ((mang xa) OR (nang x)) hoi. hieu y pham duc va hanh dai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach thu) OR (sach thieu)) ((mang xa) or (nang x)) hoi. hieu y pham duc va hanh dai cua viet".
• Adding a wildcard symbol may retrieve word variants: te ((sach thu) OR (sach thieu)) ((mang xa) or (nang x)) hoi. hieu y pham duc va hanh dai cua viet*.