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