Perhaps you should try some spelling variations:
sach tu » sach thu, cach tu, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
su tien » su kien, su hien, tu tieng
sac ky » cac ky, sai ky
di su » doi su, ki su, da su

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach tu) or (sac ky)) nang xa hoi. hieu va cac duc ((va hanh) OR (va danh)) di su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tu) OR (sac ky)) nang xa hoi. hieu va cac duc ((va hanh) OR (va danh)) di su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tu) or (sac ky)) nang xa hoi. hieu va cac duc ((va hanh) OR (va danh)) di su tien".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tu) or (sac ky)) nang xa hoi. hieu va cac duc ((va hanh) OR (va danh)) di su tien*.