Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thanh do » thanh de, thanh hoa, thanh loi
dang xay » dang van, van xay
cac tuc » cac toc, cac tu, cac tac
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
tuc va » thuc va, truc va, tuc xa

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

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