Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
thanh dat » thanh san, thanh hai, thanh van
thuc dan » thuc hanh, hoc dan, thuc vat
va triet » va thiet, va trien, ve triet
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty dang » ty xang, ky dang, ty hang
dang xa » dang xay, lang xa, dang ha
ve chim » va chim, ve cham, ve chinh
va cham » va chat, va tham

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 dang xa hoi. hieu ((ve chim) or (va cham)) thuc dan thanh dat va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty dang xa hoi. hieu ((ve chim) OR (va cham)) thuc dan thanh dat va triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ty dang xa hoi. hieu ((ve chim) or (va cham)) thuc dan thanh dat va triet*.