Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu cua » hieu qua, dieu cua, bieu cua
su sach » so sach, vu sach
cac luc » cau luc, coc luc, cac nuoc
v nang » va nang, vu nang, van nang
y nang » ky nang, ly nang, may nang
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao
va cua » va chua, via cua, ca cua

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