Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cac khoi » cac thoi, cac khoan, cach thoi
danh sai » dung sai, danh bat, danh dau
mai khoi » mai khoa, tai khoa, dai khoa
hieu van » hieu va, thien van, lieu va
sai cau » lai chau, mai chau, hai chau
va danh » va dinh, va dan, va hanh
nam xuc » cam xuc, nam xua, nam thuc
thu sac » thu sach, thu san, thu xac
ky tang » ky nang, ky dang, kho tang
mai hoi » dai hoi, lai hoi, mai doi
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) OR (cac khoi)))). hieu van nam xuc va danh sai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sac ky tang ((mai hoi) OR (((mai khoi) OR (cac khoi)))). hieu van nam xuc va danh sai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sac ky tang ((mai hoi) or (((mai khoi) OR (cac khoi)))). hieu van nam xuc va danh sai cau tren".
• Adding a wildcard symbol may retrieve word variants: thu sac ky tang ((mai hoi) or (((mai khoi) OR (cac khoi)))). hieu van nam xuc va danh sai cau tren*.