Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
cau tren » cu tren, dau tren, ca tren
vat hanh » vat thanh, van hanh, va hanh
sach thu » sach thue, sach thieu, sach tham
hanh di » hanh vi, hanh de, hang di
va cham » va chat, va tham
hieu va » lieu va, hieu qua
sach ty » sach y, sach tu, xach tay
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
di cau » da cau, diem cau

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: te ((sach ty) OR (sach thu)) ((nang xa) OR (lang xa)) hoi. hieu va cham thuc vat hanh di cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) OR (sach thu)) ((nang xa) or (lang xa)) hoi. hieu va cham thuc vat hanh di cau tren~".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) OR (sach thu)) ((nang xa) or (lang xa)) hoi. hieu va cham thuc vat hanh di cau tren*.