Perhaps you should try some spelling variations:
hoc thieu » toc thieu, hoc hien
cach manh » cach mang, cach nhanh, sach danh
cong cong » cong dong, trong cong, dang cong
dung cong » dung trong
doc hieu » toc thieu, hoc hien
manh cua » doanh cua, ban cua
dan than » dan chan, ban than, van than
than tap » toan tap, han tap, phan tap

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc hieu) OR (hoc thieu)) sach - cach manh cua ((cong cong) OR (dung cong)) dan than tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc hieu) or (hoc thieu)) sach - cach manh cua ((cong cong) OR (dung cong)) dan than tap~".
• Adding a wildcard symbol may retrieve word variants: ((doc hieu) or (hoc thieu)) sach - cach manh cua ((cong cong) OR (dung cong)) dan than tap*.