Perhaps you should try some spelling variations:
danh vit » danh viet, dinh viet, dang viet
thuc day » thuc dan, thuc vat
su sach » so sach, vu sach
thuc va » thuc vat, thuc dan
sach ky » sac ky, sach y, sach ty
ca viet » va viet, co viet, hoa viet
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
ma hoi » xa hoi, ma hoa, me hoi
vit ca » viet ca, viet cau
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: su sach ky sang ((ma hoi) or (mai hoi)). hieu ve nam ((thuc va) OR (thuc day)) danh vit ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang ((ma hoi) OR (mai hoi)). hieu ve nam ((thuc va) OR (thuc day)) danh vit ca viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky sang ((ma hoi) or (mai hoi)). hieu ve nam ((thuc va) OR (thuc day)) danh vit ca viet".
• Adding a wildcard symbol may retrieve word variants: su sach ky sang ((ma hoi) or (mai hoi)). hieu ve nam ((thuc va) OR (thuc day)) danh vit ca viet*.