Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cua viet » ca viet, hoa viet, cua vat
cam thuc » am thuc, nam thuc, cam thu
nang mai » nang ma, lang mai, nang cai
nang tai » hang tai, tang tai, sang tai
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, va danh
so sach » so sanh, bo sach, co sach
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
sach v » sach va, sach y, sach 2

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach v ((nang mai) or (nang tai)) hoi. hieu ve cam thuc ((va hanh) or (ban thanh)) vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v ((nang mai) OR (nang tai)) hoi. hieu ve cam thuc ((va hanh) OR (ban thanh)) vai cua viet.
• Adding a wildcard symbol may retrieve word variants: so sach v ((nang mai) or (nang tai)) hoi. hieu ve cam thuc ((va hanh) or (ban thanh)) vai cua viet*.