Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
ke phan » ve phan, kenh phan, ke thang
sach ty » sach y, sach tu, sach thu
so sach » so sanh, bo sach, co sach
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
hieu ke » hieu kem, chieu ke, hieu ky
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty ((nang xa) OR (lang xa)) hoi. hieu ke phan tu ((van hanh) or (ban thanh)) vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty ((nang xa) OR (lang xa)) hoi. hieu ke phan tu ((van hanh) OR (ban thanh)) vi su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty ((nang xa) OR (lang xa)) hoi. hieu ke phan tu ((van hanh) or (ban thanh)) vi su triet*".