Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cam thuc » am thuc, nam thuc, can thuc
thanh de » hanh de, thanh ve, thanh do
sach thu » sach thue, sach thieu, sach tham
lang van » dang van, tang van, hoang van
cam thu » nam thu, cac thu, ca thu
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, xach tay
van hoi » van hoa, van hoc, van hoe
de cua » le cua, te cua, dieu cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ty) or (sach thu)) lang van hoi. hieu ve ((cam thuc) OR (cam thu)) ban thanh de cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) lang van hoi. hieu ve ((cam thuc) OR (cam thu)) ban thanh de cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) or (sach thu)) lang van hoi. hieu ve ((cam thuc) OR (cam thu)) ban thanh de cua vat".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach thu)) lang van hoi. hieu ve ((cam thuc) OR (cam thu)) ban thanh de cua vat*.