Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
mai khoi » mai khoa, tai khoa, cac khoi
danh dau » lanh dao, hang dau, danh tu
danh sai » dung sai, danh bat, hanh san
hieu van » hieu va, thien van, lieu va
mai hoi » dai hoi, lai hoi, mai doi
nam xuc » cam xuc, nam xua, nam thuc
ky tang » ky nang, ky dang, kho tang
thu sac » thu sach, thu san, thu xac
sac ky » cac ky, sai ky
xuc va » duc va, tuc va, luc va

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 tang ((mai hoi) or (mai khoi)). hieu van nam xuc va ((danh sai) OR (danh dau)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sac ky tang ((mai hoi) OR (mai khoi)). hieu van nam xuc va ((danh sai) OR (danh dau)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sac ky tang ((mai hoi) or (mai khoi)). hieu van nam xuc va ((danh sai) OR (danh dau)) cau tren".
• Adding a wildcard symbol may retrieve word variants: thu sac ky tang ((mai hoi) or (mai khoi)). hieu van nam xuc va ((danh sai) OR (danh dau)) cau tren*.