Perhaps you should try some spelling variations:
hanh vai » hanh vi, hanh va, hanh tai
vien cac » vien bach, vien dai, vien da
thu sac » thu sach, thu san, thu xac
va hanh » van hanh, va thanh, va danh
ca tren » cau tren, cu tren, la tren
dai hoi » dai hoc, dai hai, dai moi
mai hoi » mai khoi, lai hoi, mai doi
ky sang » ky nang, ky dang, ky tang
sac ky » cac ky, sai ky
luc va » duc va, tuc va, loc va
vai ca » vai cac, vai cua, bai ca
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 sac ky sang ((mai hoi) OR (dai hoi)). hieu ((ve cam) or (vien cac)) luc va hanh vai ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sac ky sang ((mai hoi) OR (dai hoi)). hieu ((ve cam) OR (vien cac)) luc va hanh vai ca tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sac ky sang ((mai hoi) OR (dai hoi)). hieu ((ve cam) or (vien cac)) luc va hanh vai ca tren".
• Adding a wildcard symbol may retrieve word variants: thu sac ky sang ((mai hoi) OR (dai hoi)). hieu ((ve cam) or (vien cac)) luc va hanh vai ca tren*.