referral websites

we have two clients. in client A’s Google Analytics, in the channel section, I’ve found that client B referred to A. I’ve gone to each page of B website that GA recognized, inspect on each page. but I can not find any ahref link to the client A. where is the problem?

Is it in GA setting? or is in the client’s side. It’s too vital for me to discover.please help me in thi sisuue