Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thuc ban » thuoc ban, thuc dan, thu ban
cam thuc » am thuc, nam thuc, cam thu
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
lang xa » lang ha, dang xay, lang van
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky ((lang xa) or (nang ma)) hoi. hieu va cam thuc ban thanh ((vi luu) or (vi lua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((lang xa) OR (nang ma)) hoi. hieu va cam thuc ban thanh ((vi luu) OR (vi lua)) tre.
• Adding a wildcard symbol may retrieve word variants: vu sach ky ((lang xa) or (nang ma)) hoi. hieu va cam thuc ban thanh ((vi luu) or (vi lua)) tre*.