Perhaps you should try some spelling variations:
thuc dan » thuc hanh, thuc vat
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
da cua » dai cua, day cua, dan cua
dan da » dan dat, dan ca, dan va
ve cac » va cac, vien cac
y tang » ky tang, 6 tang, 5 tang
7 tang » 6 tang
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((y tang) OR (7 tang)) van hoa. hieu ve cac ((thuc dan) or (hoc dan)) dan da cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y tang) OR (7 tang)) van hoa. hieu ve cac ((thuc dan) OR (hoc dan)) dan da cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y tang) OR (7 tang)) van hoa. hieu ve cac ((thuc dan) or (hoc dan)) dan da cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y tang) OR (7 tang)) van hoa. hieu ve cac ((thuc dan) or (hoc dan)) dan da cua te*.