Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
thuc dan » thuc hanh, hoc dan, thuc vat
sach dao » lanh dao
nang mai » nang ma, nang tai, lang mai
thuc va » thuc vat, thuc day
sach va » sach xa, sach ha, sach nha
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
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: so ((sach va) or (sach dao)) nang mai hoi. hieu ve cam ((thuc va) OR (thuc dan)) hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sach va) OR (sach dao)) nang mai hoi. hieu ve cam ((thuc va) OR (thuc dan)) hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sach va) or (sach dao)) nang mai hoi. hieu ve cam ((thuc va) OR (thuc dan)) hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: so ((sach va) or (sach dao)) nang mai hoi. hieu ve cam ((thuc va) OR (thuc dan)) hanh vi cua viet*.