Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
thu sach » tu sach, thuoc sach, thu hoach
ban hanh » ban hang
dat tren » dat trong, dua tren
may hoi » may thoi, tay hoi, mai hoi
xuc ban » duc ban, cuc ban, quoc ban
y mang » cay mang
va cau » van cau, va dau, va cao
vi dat » voi dat, vi dai, va dat

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (thuat sach)) y mang may hoi. hieu ((va cau) OR (va cac)) xuc ban hanh vi dat tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuat sach)) y mang may hoi. hieu ((va cau) OR (va cac)) xuc ban hanh vi dat tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thuat sach)) y mang may hoi. hieu ((va cau) OR (va cac)) xuc ban hanh vi dat tren".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuat sach)) y mang may hoi. hieu ((va cau) OR (va cac)) xuc ban hanh vi dat tren*.