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

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) or (ly nang)) xa hoi. hieu qua cac luc va ((dan va) OR (doan va)) cao viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (ly nang)) xa hoi. hieu qua cac luc va ((dan va) OR (doan va)) cao viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) or (ly nang)) xa hoi. hieu qua cac luc va ((dan va) OR (doan va)) cao viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) or (ly nang)) xa hoi. hieu qua cac luc va ((dan va) OR (doan va)) cao viet*.