Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
danh vai » danh sai, danh va, doanh van
cau tren » cu tren, dau tren, ca tren
kho tang » cao tang
lai hoi » lai hoa, lai roi, mai hoi
dai hoi » dai hoc, dai hai, dai moi
hieu ve » hieu va, hieu van
cam duc » cam xuc, cao duc, pham duc
va danh » va dinh, va dan, va hanh
ky sang » ky nang, ky dang, ky tang
vai cau » va cau, van cau, vai cac
ve cam » ve cham, ve cac, va cam

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 ((ky sang) or (kho tang)) ((lai hoi) OR (dai hoi)). hieu ve cam duc va danh vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky sang) OR (kho tang)) ((lai hoi) OR (dai hoi)). hieu ve cam duc va danh vai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((ky sang) or (kho tang)) ((lai hoi) OR (dai hoi)). hieu ve cam duc va danh vai cau tren".
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky sang) or (kho tang)) ((lai hoi) OR (dai hoi)). hieu ve cam duc va danh vai cau tren*.