Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
dan thanh » dang thanh, danh thanh, ban thanh
va triet » va thiet, va trien, ve triet
sach thu » sach thue, sach thieu, sach tham
thuc dan » thuc hanh, hoc dan, thuc vat
va chat » van chat, va phat, cao chat
ve chim » va chim, ve cham, ve chinh
sach ty » sach y, sach tu, xach tay
dung ha » dung va, dung he, dung khoa
ha hoi » hoa hoi, ha noi, xa hoi

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