Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
quan cau » quang cao, toan cau, quan ha
cua viet » ca viet, cua dieu, va viet
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
cau luc » cau truc, cau phuc
y nang » ky nang, ly nang, v nang
luc va » duc va, tuc va, loc va
va ban » van ban, va bai, va bao

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang xa hoi. hieu quan cau luc va ban va ((((cua viet) or (hoa viet))) or (cua vat))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang xa hoi. hieu quan cau luc va ban va ((((cua viet) OR (hoa viet))) OR (cua vat)).
• Adding a wildcard symbol may retrieve word variants: tu sach y nang xa hoi. hieu quan cau luc va ban va ((((cua viet) or (hoa viet))) or (cua vat))*.