Perhaps you should try some spelling variations:
hanh tranh » hanh trinh, hanh trang, lanh tranh
nhung cong » dung cong, thong cong, hang cong
hieu tach » hieu cach, chiet tach, chieu sach
doc hieu » toc thieu, hoc thieu, hoc hien
cong cao » cong cau, cong cac, cong co
chat tap » chat tai, chat thai, chat va

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu tach - ((hanh tranh) or (canh tranh)) va nhung cong cao chat tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu tach - ((hanh tranh) OR (canh tranh)) va nhung cong cao chat tap.
• Adding a wildcard symbol may retrieve word variants: doc hieu tach - ((hanh tranh) or (canh tranh)) va nhung cong cao chat tap*.