Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
sang mai » sang ma, sang tai, hoang mai
cua viet » ca viet, hoa viet, cua vat
lang mai » lang dai, lang hai, lang man
thuoc va » thuc va, thuoc ma, thuong va
vu sach » vu bach, su sach, vu khach
va hanh » van hanh, va thanh, va danh
va viet » hoa viet, san viet, mai viet
hieu ve » hieu va, hieu van
ve nam » he nam, va nam, le nam

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach _ ((sang mai) or (lang mai)) hoi. hieu ve nam thuoc va hanh vi ((cua viet) or (va viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach _ ((sang mai) OR (lang mai)) hoi. hieu ve nam thuoc va hanh vi ((cua viet) OR (va viet)).
• Adding a wildcard symbol may retrieve word variants: vu sach _ ((sang mai) or (lang mai)) hoi. hieu ve nam thuoc va hanh vi ((cua viet) or (va viet))*.