Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
thanh dai » thanh hai, thanh dat, thanh oai
va triet » va thiet, va trien, ve triet
hieu van » hieu va, thien van, lieu va
cau duc » cao duc, cau luc, chu duc
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang ro » nang co, nang ho, nang ra
van cau » van dau, van hau, van chat
nang o » nang co, nang ho, nang x

You may be able to get more results by adjusting your search query.

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