Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
hieu ve » hieu va
lang ha » long ha
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
ha hoi » hoa hoi, ha noi, xa hoi
y lang » o lang, _ lang, tay lang
vi cua » vai cua
di cua » dai cua, doi cua, de cua

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: toc sach y lang ha hoi. ((hieu ve) OR (hieu van)) cam thuc va hanh ((vi cua) OR (di cua)) te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y lang ha hoi. ((hieu ve) or (hieu van)) cam thuc va hanh ((vi cua) OR (di cua)) te~".
• Adding a wildcard symbol may retrieve word variants: toc sach y lang ha hoi. ((hieu ve) or (hieu van)) cam thuc va hanh ((vi cua) OR (di cua)) te*.