Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
phap thuc » phap thu, phap hoc, phap tu
toc sach » hoc sach, doc sach, thuoc sach
van hoi » van hoa, van hoc, van loi
van hoe » van hoa, van hoc, van hieu
hieu ve » hieu va, hieu van
ve phap » va phap, de phap, ve phan
vai cua » dai cua, hai cua, lai cua
y tang » ky tang, 6 tang, 7 tang
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 y tang ((van hoi) OR (van hoe)). hieu ve phap thuc vat thanh ((vi cua) or (vai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y tang ((van hoi) OR (van hoe)). hieu ve phap thuc vat thanh ((vi cua) OR (vai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y tang ((van hoi) OR (van hoe)). hieu ve phap thuc vat thanh ((vi cua) or (vai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: toc sach y tang ((van hoi) OR (van hoe)). hieu ve phap thuc vat thanh ((vi cua) or (vai cua)) tre*.