Perhaps you should try some spelling variations:
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
va dinh » van dinh, va kinh, va tinh
so viet » hoc viet
cac luc » cau luc, cac nuoc, cac cuoc
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
y nang » ky nang, ly nang, v nang
tai so » tai sao, dai so, tai co

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang cao hoi. hieu ve ((cac luc) OR (coc luc)) ((va hanh) or (va dinh)) tai so viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang cao hoi. hieu ve ((cac luc) OR (coc luc)) ((va hanh) OR (va dinh)) tai so viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang cao hoi. hieu ve ((cac luc) OR (coc luc)) ((va hanh) or (va dinh)) tai so viet".
• Adding a wildcard symbol may retrieve word variants: su sach y nang cao hoi. hieu ve ((cac luc) OR (coc luc)) ((va hanh) or (va dinh)) tai so viet*.