Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
toc sach » hoc sach, doc sach, thuoc sach
lang van » tang van, hoang van, giang van
dang van » hoang van, hang va
thuc ban » thuoc ban, thuc dan, thu ban
ban hanh » ban hang
hieu va » lieu va, hieu qua
va cham » va chat, va tham
vai cua » dai cua, hai cua, lai cua
vi cua » di cua

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 _ ((lang van) OR (dang van)) hoi. hieu va cham thuc ban hanh ((vi cua) or (vai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach _ ((lang van) OR (dang van)) hoi. hieu va cham thuc ban hanh ((vi cua) OR (vai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach _ ((lang van) OR (dang van)) hoi. hieu va cham thuc ban hanh ((vi cua) or (vai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: toc sach _ ((lang van) OR (dang van)) hoi. hieu va cham thuc ban hanh ((vi cua) or (vai cua)) tre*.