Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
qua cac » cua cac
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
va dan » ca dan, va dao, va dap
va dau » va dao
va cua » va chua, via cua, ca cua

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) or (va dau)) va cua 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) OR (va dau)) va cua 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) or (va dau)) va cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) OR (ly nang)) xa hoi. hieu qua cac luc ((va dan) or (va dau)) va cua viet*.