Perhaps you should try some spelling variations:
sach duoc » sach nuoc, sach dao, sach dung
cham thuc » nham thuc, pham thuc, tham thuc
sach vuc » sach nuoc, sach truc, sach bac
vat hanh » vat thanh, van hanh, va hanh
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
nang o » nang co, nang ho, nang ro
di cuu » di cua, dinh cuu
di cau » da cau, diem cau
o hai » co hai, so hai, o lai

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: su ((sach vuc) OR (sach duoc)) nang o hai. hieu ve cham thuc vat hanh ((di cuu) OR (di cau)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach vuc) or (sach duoc)) nang o hai. hieu ve cham thuc vat hanh ((di cuu) OR (di cau)) tre~".
• Adding a wildcard symbol may retrieve word variants: su ((sach vuc) or (sach duoc)) nang o hai. hieu ve cham thuc vat hanh ((di cuu) OR (di cau)) tre*.