Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
vat hanh » vat thanh, van hanh, va hanh
tu sach » thu sach, te sach, tu cach
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
su sach » so sach, vu sach
ma noi » ha noi, ma moi, va noi
de cua » le cua, dieu cua
te cua » tue cua, le 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) or (su sach)) ky tang ma noi. hieu ve cham thuc vat hanh ((de cua) or (te cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky tang ma noi. hieu ve cham thuc vat hanh ((de cua) OR (te cua)) tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky tang ma noi. hieu ve cham thuc vat hanh ((de cua) or (te cua)) tre*.