Perhaps you should try some spelling variations:
sach thien » sach thieu, sach tien, cach thien
cau triet » cau trieu, su triet, cua triet
dua tren » dung tren
dinh tri » chinh tri
hieu van » hieu va, thien van, lieu va
va dinh » van dinh, va kinh, va tinh
su sach » so sach, vu sach
van cau » van dau, van hau, van chat
truc va » thuc va, thuc vat, trung va
ban xa » ban ma, ban da, ban a

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 thien ((ban xa) OR (ban va)) hoi. hieu van cau truc va dinh tri ((dua tren) or (cau triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach thien ((ban xa) OR (ban va)) hoi. hieu van cau truc va dinh tri ((dua tren) OR (cau triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach thien ((ban xa) OR (ban va)) hoi. hieu van cau truc va dinh tri ((dua tren) or (cau triet))".
• Adding a wildcard symbol may retrieve word variants: su sach thien ((ban xa) OR (ban va)) hoi. hieu van cau truc va dinh tri ((dua tren) or (cau triet))*.