Perhaps you should try some spelling variations:
xang van » dang van, tang van, lang van
van hieu » cao hieu
cau thuc » cau truc, cuu thuc, can thuc
cua viet » ca viet, hoa viet, cua vat
so sach » so sanh, bo sach, hoc sach
co sach » bo sach, cuon sach, hoc sach
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
ve cau » ke cau, va cau, ve cac
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) or (co sach)) ty xang van hieu. hieu ve cau thuc va hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (co sach)) ty xang van hieu. hieu ve cau thuc va hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (co sach)) ty xang van hieu. hieu ve cau thuc va hanh vi cua viet*.