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