Exhibit 24.2

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below does hereby constitute and appoint John H. Kispert and Randy W. Furr, and each of them, to be his true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities, to sign the registration statement with which this Power of Attorney is filed and any and all amendments thereto (including without limitation any post-effective amendments thereto and any registration statement pursuant to Rule 462(b)), and to file each of the same, with all exhibits thereto and all other documents in connection therewith, with the Securities and Exchange Commission, and every act and thing necessary or desirable to be done, as fully to all intents and purposes as he might or could do in person, thereby ratifying and confirming all that said attorneys-in-fact and agents, or any of them, or their or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof.