Perhaps you should try some spelling variations:
ve triet » va trien, su triet
va thanh » gia thanh, ban thanh, le thanh
hieu van » hieu va, thien van, lieu va
cau duc » cao duc, cau luc, chu duc
va tinh » may tinh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
van cau » van dau, van hau, van chat
co hoi » co hoc, co loi
lam ve » la ve, lam vu, nam ve
o hoi » o hoc, 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 ky nang ((o hoi) or (co hoi)). hieu van cau duc ((va thanh) OR (va tinh)) lam ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (co hoi)). hieu van cau duc ((va thanh) OR (va tinh)) lam ve triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hoi) or (co hoi)). hieu van cau duc ((va thanh) OR (va tinh)) lam ve triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (co hoi)). hieu van cau duc ((va thanh) OR (va tinh)) lam ve triet*.