Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
thanh dai » thanh hai, thanh tai, thanh dat
va thanh » gia thanh, ban thanh, va tinh
cau duc » cao duc, cau luc, chu duc
hieu va » lieu va, hieu qua
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
va cau » van cau, va cac, va dau
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa

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