Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va tinh » may tinh
cac tuc » cac toc, cac tu, cac tac
hieu ve » hieu va, hieu van
so dang » su dang, so dan, so dung
ve cac » va cac, vien cac
tuc va » thuc va, truc va, tuc xa
o dang » xo dang, do dang, o dong
vi cua » vai 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 ((o dang) OR (so dang)) van hoa. hieu ve cac tuc va tinh ((vi cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((o dang) OR (so dang)) van hoa. hieu ve cac tuc va tinh ((vi cua) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((o dang) OR (so dang)) van hoa. hieu ve cac tuc va tinh ((vi cua) or (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((o dang) OR (so dang)) van hoa. hieu ve cac tuc va tinh ((vi cua) or (dai cua)) tre*.