Perhaps you should try some spelling variations:
van dung » van dong, xay dung, tin dung
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, mang xa, ang xa
lang xa » lang ha, dang xay, lang van
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
tuc van » thuc van, truc van, tuc va
tai su » tai so, tai tu, lai 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 sach ky ((((nang xa) OR (lang xa))) or (nang ma)) hoi. hieu va cac tuc van dung tai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((((nang xa) OR (lang xa))) OR (nang ma)) hoi. hieu va cac tuc van dung tai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((((nang xa) OR (lang xa))) or (nang ma)) hoi. hieu va cac tuc van dung tai su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((((nang xa) OR (lang xa))) or (nang ma)) hoi. hieu va cac tuc van dung tai su triet*.