Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
dang xay » dang van, van xay
hanh va » hang va, hanh vi
truc va » thuc va, thuc vat, trung va
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
tuc va » thuc va, tuc xa, duc va
va hai » van hai, va chai, va khai

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 y ((nang xa) or (dang xay)) hoi. hieu va hai ((tuc va) OR (truc va)) hanh va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang xa) OR (dang xay)) hoi. hieu va hai ((tuc va) OR (truc va)) hanh va su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang xa) or (dang xay)) hoi. hieu va hai ((tuc va) OR (truc va)) hanh va su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang xa) or (dang xay)) hoi. hieu va hai ((tuc va) OR (truc va)) hanh va su triet*.