Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
thanh va » thanh van, hanh va, thanh ha
thuc dan » thuc hanh, hoc dan, thuc vat
va pham » van pham, va phap, va phan
sach ty » sach y, sach thu, xach tay
sach tu » sach thu, cach tu, sach uu
cua tre » cua te, cuu tre, cua triet
va hoi » xa hoi, va hoc, va hoa
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ty) OR (sach tu)) hang va hoi. hieu ((va pham) or (va phat)) thuc dan thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach tu)) hang va hoi. hieu ((va pham) OR (va phat)) thuc dan thanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach tu)) hang va hoi. hieu ((va pham) or (va phat)) thuc dan thanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach tu)) hang va hoi. hieu ((va pham) or (va phat)) thuc dan thanh va cua tre*.