Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
ve triet » va trien
su triet » su viet, su tien
can thuc » dan thuc, van thuc, cay thuc
vien can » vien canh, vien cac, vien cao
dang xay » dang van, van xay
lang xa » lang ha, lang van
thuc va » thuc vat, thuc dan, thuc day
va hang » van hang, va nang, va lang
hang vi » hang va, hanh vi, hang di
vu sach » vu bach, su sach, vu khach
sach v » sach va, sach y, sach 2

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach v ((lang xa) or (dang xay)) hoi. hieu vien can thuc va hang vi ((su triet) OR (ve triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach v ((lang xa) OR (dang xay)) hoi. hieu vien can thuc va hang vi ((su triet) OR (ve triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach v ((lang xa) or (dang xay)) hoi. hieu vien can thuc va hang vi ((su triet) OR (ve triet))".
• Adding a wildcard symbol may retrieve word variants: vu sach v ((lang xa) or (dang xay)) hoi. hieu vien can thuc va hang vi ((su triet) OR (ve triet))*.