Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
va thanh » gia thanh, ban thanh, va tinh
cua viet » ca viet, hoa viet, cua vat
va triet » va thiet, va trien, ve triet
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
hieu va » hieu qua
cau duc » cao duc, cau luc, chu duc
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky nang o hoi. ((hieu va) OR (lieu va)) cau duc va thanh dai ((cua viet) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang o hoi. ((hieu va) OR (lieu va)) cau duc va thanh dai ((cua viet) OR (va triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang o hoi. ((hieu va) OR (lieu va)) cau duc va thanh dai ((cua viet) or (va triet))".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang o hoi. ((hieu va) OR (lieu va)) cau duc va thanh dai ((cua viet) or (va triet))*.