Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh tai » thanh hai, thanh toan, doanh tai
hieu van » hieu va, thien van, lieu va
va trien » va truyen, va tuyen, va tieng
ve triet » su triet
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
duc ban » duc tan, duc van, dua ban
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
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: tu sach ky nang o hoi. hieu van cau duc ban thanh tai ((((va trien) OR (va thiet))) or (ve triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang o hoi. hieu van cau duc ban thanh tai ((((va trien) OR (va thiet))) OR (ve triet))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang o hoi. hieu van cau duc ban thanh tai ((((va trien) OR (va thiet))) or (ve triet))*".