Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
thanh da » thanh dat, thanh dam, thanh dan
van cham » van chat, van tham, va cham
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
xang xa » lang xa, mang xa, dang xay
soc gia » toc gia, hoc gia, quoc gia
so sach » so sanh, bo sach, co sach
ang xa » lang xa, mang xa, dang xay
so gia » so giai, so giao, ho gia
da cau » dat cau, va cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach thu ((xang xa) or (ang xa)) hoi. hieu van cham ((soc gia) OR (so gia)) thanh da cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach thu ((xang xa) OR (ang xa)) hoi. hieu van cham ((soc gia) OR (so gia)) thanh da cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach thu ((xang xa) or (ang xa)) hoi. hieu van cham ((soc gia) OR (so gia)) thanh da cau tren".
• Adding a wildcard symbol may retrieve word variants: so sach thu ((xang xa) or (ang xa)) hoi. hieu van cham ((soc gia) OR (so gia)) thanh da cau tren*.