Perhaps you should try some spelling variations:
sach thi » sach thu, sach tai, sach thieu
va triet » va thiet, va trien, ve triet
hanh lai » hanh lam, hanh tai, thanh lap
cac thuc » cach thuc, cac thu, can thuc
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
thi lan » thi hanh, thi nang, thi lien
ve cac » va cac, vien cac
ha hoi » hoa hoi, xa hoi, va hoi

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thi lan ((ha hoi) OR (ha noi)). hieu ve cac thuc va hanh lai ((va triet) OR (cua vat))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thi lan ((ha hoi) OR (ha noi)). hieu ve cac thuc va hanh lai ((va triet) or (cua vat))~".
• Adding a wildcard symbol may retrieve word variants: tu sach thi lan ((ha hoi) OR (ha noi)). hieu ve cac thuc va hanh lai ((va triet) or (cua vat))*.