All communications hereunder will be in writing and effective only on receipt, and, if sent to the Representative, will be mailed, delivered or telefaxed to Credit Suisse Securities (USA) LLC, Eleven Madison Avenue, New York, New York 10010-3629, attention of IBCM-Legal, fax no. (212) 325-4296; or, if sent to the Company, will be mailed, delivered or telefaxed to (918) 524-8587 and confirmed to it at Two Warren Place, 6120 S. Yale Avenue, Suite 1500, Tulsa, Oklahoma 74136-4231, attention of General Counsel.