Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
nang xa » nang x, lang xa, mang xa
te sach » toc sach
vi va » vi van, vai va, vu va

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