Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
kho tang » cao tang
sach kho » bach khoa, sach dao, sach nha
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
ma hoi » xa hoi, ma hoa, me hoi
vi cua » vai cua, di cua

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 kho tang ((ma hoi) or (mai hoi)). hieu ve cac ((thuc va) or (tuc xa)) hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach kho tang ((ma hoi) OR (mai hoi)). hieu ve cac ((thuc va) OR (tuc xa)) hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: su sach kho tang ((ma hoi) or (mai hoi)). hieu ve cac ((thuc va) or (tuc xa)) hanh vi cua viet*.