Any bank holding a note secured by an Adjusted Service Certificate may sell the note to any bank authorized to make a loan to a veteran and deliver the certificate to such bank. In case a note secured by an Adjusted Service Certificate is sold or transferred, the bank selling, discounting or rediscounting the note is required by law to notify the veteran promptly by mail at his last known post office address. No Adjusted Service Certificate is negotiable or assignable, or may serve as security for a loan, except as provided in section 502 of the World War Adjusted Compensation Act, as amended. Any negotiation, assignment or loan made in violation of section 502 of the World War Adjusted Compensation Act is void. In case of sale, discount or rediscount by the bank which made the loan, the note or notes should be accompanied by the affidavit required by §11.85.