Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
thuc dan » thuc hanh, hoc dan, thuc vat
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
ve chim » va chim, ve cham, ve chinh
va cham » va chat, va tham
ang xa » lang xa, mang xa, dang xay
ty ang » ty xang, ty hang, ty anh
hai va » hai van, thai va, mai va

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 ty ang xa hoi. hieu ((ve chim) or (va cham)) thuc dan thanh ((hai va) OR (hoi va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ang xa hoi. hieu ((ve chim) OR (va cham)) thuc dan thanh ((hai va) OR (hoi va)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ang xa hoi. hieu ((ve chim) or (va cham)) thuc dan thanh ((hai va) OR (hoi va)) triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ang xa hoi. hieu ((ve chim) or (va cham)) thuc dan thanh ((hai va) OR (hoi va)) triet*.