Perhaps you should try some spelling variations:
hoc viet » hoc hien
nam thuc » nam thuoc, am thuc, nam thu
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
sac ky » cac ky
ma hoi » xa hoi, ma hoa, me hoi
ve nam » he nam, va nam, le nam
vi hoc » li hoc, va hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: so ((sac ky) or (sai ky)) tang ((ma hoi) or (mai hoi)). hieu ve nam thuc va danh vi hoc viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sac ky) OR (sai ky)) tang ((ma hoi) OR (mai hoi)). hieu ve nam thuc va danh vi hoc viet.
• Adding a wildcard symbol may retrieve word variants: so ((sac ky) or (sai ky)) tang ((ma hoi) or (mai hoi)). hieu ve nam thuc va danh vi hoc viet*.