Perhaps you should try some spelling variations:
dang xay » dang van
sach tu » sach thu, cach tu, sach ty
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
su viet » so viet
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)) ((dang xay) OR (van xay)) hoi. hieu va cac duc va hanh di su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach tu) OR (sac ky)) ((dang xay) OR (van xay)) hoi. hieu va cac duc va hanh di su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach tu) or (sac ky)) ((dang xay) OR (van xay)) hoi. hieu va cac duc va hanh di su viet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach tu) or (sac ky)) ((dang xay) OR (van xay)) hoi. hieu va cac duc va hanh di su viet*.