Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
toc sach » hoc sach, doc sach, thuoc sach
cam thuc » am thuc, nam thuc, cam thu
thuc ban » thuoc ban, thuc dan, thu ban
vai cua » hai cua, lai cua, bai cua
hieu ve » hieu va, hieu van
van hoe » van hoa, van hoc, van hieu
van hoi » van hoa, van hoc, van loi
ve cam » ve cham, ve cac, va cam
sach o » sach lo, sac o, sach y
o dang » xo dang, do dang, so dang

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach o dang ((van hoi) or (van hoe)). hieu ve cam thuc ban thanh ((vai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach o dang ((van hoi) OR (van hoe)). hieu ve cam thuc ban thanh ((vai cua) OR (dai cua)) tre.
• Adding a wildcard symbol may retrieve word variants: toc sach o dang ((van hoi) or (van hoe)). hieu ve cam thuc ban thanh ((vai cua) or (dai cua)) tre*.