Perhaps you should try some spelling variations:
ban hanh » ban hang
su triet » su viet, su tien, ve triet
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
su sac » su sach, su cac, su xac
sac ky » cac ky, sai 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: su sac ky ((nang xa) OR (nang ma)) hoi. hieu va cac du ((ban hanh) or (van minh)) vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky ((nang xa) OR (nang ma)) hoi. hieu va cac du ((ban hanh) OR (van minh)) vi su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sac ky ((nang xa) OR (nang ma)) hoi. hieu va cac du ((ban hanh) or (van minh)) vi su triet*".