Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
ban hanh » ban hang
luc ban » duc ban, cuc ban, luc bat
cau luc » cau truc, cau phuc
hieu va » hieu qua
so sach » bo sach, co sach, hoc sach
hang xa » hoang xa, hang va, hang ca
ty hang » ly hang, ty xang, thi hang
so sanh » do sanh
vi cau » va cau, ve cau, di 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) OR (so sanh)) ty hang xa hoi. ((lieu va) or (hieu va)) cau luc ban hanh vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (so sanh)) ty hang xa hoi. ((lieu va) OR (hieu va)) cau luc ban hanh vi cau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) OR (so sanh)) ty hang xa hoi. ((lieu va) or (hieu va)) cau luc ban hanh vi cau tren*".