Perhaps you should try some spelling variations:
nhung cuong » nhung cong, hung cuong, nhung chong
thieu sach » chieu sach, thien hach, hieu cach
trinh chat » tinh chat, trinh luat, trinh han
trinh thuc » trinh tu, trinh thi
hoc thieu » toc thieu, hoc hien
tap toan » tap quan, bai toan
tap doan » tap quan

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: hoc thieu sach - hanh ((trinh chat) OR (trinh thuc)) nhung cuong ((tap toan) OR (tap doan)) tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thieu sach - hanh ((trinh chat) or (trinh thuc)) nhung cuong ((tap toan) OR (tap doan)) tap~".
• Adding a wildcard symbol may retrieve word variants: hoc thieu sach - hanh ((trinh chat) or (trinh thuc)) nhung cuong ((tap toan) OR (tap doan)) tap*.