Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
cua triet » cua viet, su triet, va triet
va thanh » gia thanh, ban thanh, va tinh
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang o » nang co, nang ho, nang ro
va cau » van cau, va dau, va cao
o hoi » co hoi, o hoc, o hai
thiet » thieu

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