Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
thuoc va » thuc va, thuoc ma, thuong va
ky sang » ky nang, ky dang, ky tang
ca viet » va viet, co viet, san viet
hanh di » hanh vi, hanh de, hang di
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
su xac » pu xac, su cac
ve nam » he nam, va nam, le nam
xac ky » cac ky, sac ky, bac ky
ma hoi » mai hoi, xa hoi, me hoi

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su xac ky sang ((ma hoi) or (ma hoa)). hieu ve nam thuoc va hanh di ((ca viet) OR (hoa viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su xac ky sang ((ma hoi) OR (ma hoa)). hieu ve nam thuoc va hanh di ((ca viet) OR (hoa viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su xac ky sang ((ma hoi) or (ma hoa)). hieu ve nam thuoc va hanh di ((ca viet) OR (hoa viet))".
• Adding a wildcard symbol may retrieve word variants: su xac ky sang ((ma hoi) or (ma hoa)). hieu ve nam thuoc va hanh di ((ca viet) OR (hoa viet))*.