Perhaps you should try some spelling variations:
dong khoan » dong khoa, dung khoa, dong hoa
khoan hoi » khoan nhoi, khoa hoi, khoa hoc
thu sach » thuat sach, thuoc sach, thu hoach
ban tinh » ban thanh, quan tinh, ban hanh
tu sach » su sach, te sach, tu cach
cam cuu » cham cuu, cap cuu
tinh vi » trinh vi, tinh voi, tinh va
cuu ban » cuu van, cua ban, cuu san
hieu ve » hieu va, hieu van
ty dong » tay dong, tu dong, ly dong
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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) or (thu sach)) ty dong khoan hoi. ((hieu ve) or (lieu va)) cam cuu ban tinh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty dong khoan hoi. ((hieu ve) OR (lieu va)) cam cuu ban tinh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ty dong khoan hoi. ((hieu ve) or (lieu va)) cam cuu ban tinh vi cua tre*.