Perhaps you should try some spelling variations:
quan pham » tuan pham, quan phap, quang phat
hieu quan » hieu qua, lieu quan, thien quan
dang xay » dang van, van xay
cua viet » ca viet, cua vat, cua dieu
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
dang xa » lang xa, dang ha, dang va
va hanh » van hanh, va thanh, va danh

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((dang xa) OR (dang xay)) hoi. hieu quan pham duc va hanh vi ((cua viet) OR (hoa viet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((dang xa) OR (dang xay)) hoi. hieu quan pham duc va hanh vi ((cua viet) or (hoa viet))~".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((dang xa) OR (dang xay)) hoi. hieu quan pham duc va hanh vi ((cua viet) or (hoa viet))*.