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
van hang » van khang, van hoang, van thang
thuc van » thuc vat, thuc dan, thuc va
cac thuc » cach thuc, cac thu, can thuc
vien cac » vien bach, vien dai, vien da
dang xay » dang van, van xay
lang xa » lang ha, lang van
hang ki » hang di, hang ke, hang vi
su sach » so sach, vu sach
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: su sach v ((lang xa) or (dang xay)) hoi. hieu vien cac thuc van hang ki ((su triet) OR (ve triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach v ((lang xa) OR (dang xay)) hoi. hieu vien cac thuc van hang ki ((su triet) OR (ve triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach v ((lang xa) or (dang xay)) hoi. hieu vien cac thuc van hang ki ((su triet) OR (ve triet))".
• Adding a wildcard symbol may retrieve word variants: su sach v ((lang xa) or (dang xay)) hoi. hieu vien cac thuc van hang ki ((su triet) OR (ve triet))*.