Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
ban thanh » ban hanh, ban hang
va thanh » gia thanh, va tinh, le thanh
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
ty nang » ky nang, ty xang, ty hang
lam cua » nam cua, lam chat
tu sach » thu sach, su sach, te sach
co hoi » co hoc, co loi
o lai » o lao

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