Perhaps you should try some spelling variations:
cao viet » dao viet, co viet, ca viet
thuc van » thuc vat, thuc dan, thuc hanh
sach ky » sac ky, sach y, sach ty
hanh va » hang va, hanh vi
thuc va » thuc vat, thuc dan, thuc day
vu sach » vu bach, su sach, vu khach
hieu ve » hieu va, hieu van
ky dang » ky nang, ky danh
me hoi » le hoi
va cao » va cac, va co, va dao
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 ky dang ((me hoi) or (ma hoa)). hieu ve nam ((thuc van) OR (thuc va)) hanh va cao viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky dang ((me hoi) OR (ma hoa)). hieu ve nam ((thuc van) OR (thuc va)) hanh va cao viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky dang ((me hoi) or (ma hoa)). hieu ve nam ((thuc van) OR (thuc va)) hanh va cao viet".
• Adding a wildcard symbol may retrieve word variants: vu sach ky dang ((me hoi) or (ma hoa)). hieu ve nam ((thuc van) OR (thuc va)) hanh va cao viet*.