Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
tieu sach » chieu sach, dien sach, te sach
hanh tang » hanh trang, anh tang, hanh tung
hanh mang » nhanh mang, hanh trang, nhanh lang
cua nhung » va nhung
tap toan » tap quan, bai toan
tap doan » tap quan

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "theo tieu sach - ((hanh tang) OR (hanh mang)) cua nhung cong ((tap toan) OR (tap doan)) cau~".
• Adding a wildcard symbol may retrieve word variants: theo tieu sach - ((hanh tang) OR (hanh mang)) cua nhung cong ((tap toan) OR (tap doan)) cau*.