Perhaps you should try some spelling variations:
hieu cua » hieu qua, dieu cua, bieu cua
cua viet » ca viet, cua vat, cua dieu
tu sach » thu sach, su sach, te sach
ly nang » ky nang, ly hang, ly vang
cac luc » cau luc, coc luc, cac nuoc
y nang » ky nang, v nang, may nang
luc va » duc va, tuc va, loc va
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban va

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: tu sach ((y nang) OR (ly nang)) xa hoi. hieu cua cac luc va dan va ((cua viet) OR (hoa viet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) or (ly nang)) xa hoi. hieu cua cac luc va dan va ((cua viet) OR (hoa viet))~".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) or (ly nang)) xa hoi. hieu cua cac luc va dan va ((cua viet) OR (hoa viet))*.