Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 _______________________________________ FORM 10-Q _______________________________________ (Mark One) ý Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended March 31, 2019 or o Transition Report Pursuant to Section 13 or 15 (d) of the Securities Exchange Act of 1934 For the transition period from to Commission File No. 1-15461 ____________________________ ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q _______________________________________ (Mark One) ý Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 5100 East Skelly Drive, Suite 500, Tulsa, Oklahoma 74135 (Address of principal executive offices and zip code) Registrant's telephone number, including area code: (918) 838-8822 For the quarterly period ended December 31, 2018 or o Transition Report Pursuant to Section 1 ...