Perhaps you should try some spelling variations:
thien bang » khien bang, thien ban, thien dang
dua tren » dung tren
hieu van » hieu va, thien van, lieu va
su sach » vu sach
cau tuc » cau truc, cau tu, cau luc
dinh vi » dinh ve, dinh viet, dinh tri
xa dinh » xac dinh, va dinh, ba dinh
van cau » van dau, van hau, van chat
bang xa » lang xa, bang va, mang xa
so sach » so sanh, bo sach, co sach
cuu tre » cua tre, cau tren, cau treo

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) OR (so sach)) thien bang xa hoi. hieu van cau tuc xa dinh vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) thien bang xa hoi. hieu van cau tuc xa dinh vi ((dua tren) OR (cuu tre))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) thien bang xa hoi. hieu van cau tuc xa dinh vi ((dua tren) or (cuu tre))*".