Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hanh vai » hanh vi, hanh va, hanh tai
va hanh » van hanh, va thanh, va danh
sach ky » sac ky, sach y, sach ty
cu tren » tu tren, dua tren
lai hoi » dai hoi, lai hoa, lai roi
mai hoi » mai khoi, dai hoi, mai doi
ky sang » ky nang, ky dang, ky tang
ve cac » va cac, vien cac
xuc va » duc va, tuc va, luc va
vai cu » vai cua, van cu
ve cai » va cai, ve tai, ve cau

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