<informationTable xmlns="http://www.sec.gov/edgar/document/thirteenf/informationtable">		<infoTable>
			<nameOfIssuer>Anadarko Petroleum</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>032511107</cusip>
			<value>80133</value>
			<shrsOrPrnAmt>
				<sshPrnamt>1026559</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>SOLE</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>1026559</Sole>
				<Shared>0</Shared>
				<None>0</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Aspen Aerogels</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>04523Y105</cusip>
			<value>20968</value>
			<shrsOrPrnAmt>
				<sshPrnamt>3167322</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>SOLE</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>3167322</Sole>
				<Shared>0</Shared>
				<None>0</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>BOK Financial</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>05561Q201</cusip>
			<value>486331</value>
			<shrsOrPrnAmt>
				<sshPrnamt>6989536</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>SOLE</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>6989536</Sole>
				<Shared>0</Shared>
				<None>0</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Cognizant Technology Solutions</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>192446102</cusip>
			<value>4582</value>
			<shrsOrPrnAmt>
				<sshPrnamt>75000</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>SOLE</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>75000</Sole>
				<Shared>0</Shared>
				<None>0</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Unit Corporation</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>909218109</cusip>
			<value>20721</value>
			<shrsOrPrnAmt>
				<sshPrnamt>764052</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>SOLE</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>764052</Sole>
				<Shared>0</Shared>
				<None>0</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Calpine Corporation</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>131347304</cusip>
			<value>2227</value>
			<shrsOrPrnAmt>
				<sshPrnamt>123796</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>123796</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Express Scripts</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>30219G108</cusip>
			<value>2147</value>
			<shrsOrPrnAmt>
				<sshPrnamt>24137</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>24137</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Gaming &amp; Leisure Properties</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>36467J108</cusip>
			<value>1020</value>
			<shrsOrPrnAmt>
				<sshPrnamt>27830</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>27830</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>JPMorgan Chase &amp; Co</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>46625H100</cusip>
			<value>2267</value>
			<shrsOrPrnAmt>
				<sshPrnamt>33461</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>33461</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Liberty Broadband Corp</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>530307305</cusip>
			<value>3398</value>
			<shrsOrPrnAmt>
				<sshPrnamt>66421</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>66421</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Liberty Global - Series C</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>G5480U120</cusip>
			<value>1573</value>
			<shrsOrPrnAmt>
				<sshPrnamt>33339</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>33339</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Liberty Global - USD0.01A</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>G5480U104</cusip>
			<value>784</value>
			<shrsOrPrnAmt>
				<sshPrnamt>15337</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>15337</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Mastercard CL A</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>57636Q104</cusip>
			<value>834</value>
			<shrsOrPrnAmt>
				<sshPrnamt>8921</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>8921</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Microsoft Corp</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>594918104</cusip>
			<value>4107</value>
			<shrsOrPrnAmt>
				<sshPrnamt>93022</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>93022</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Sirius XM Holdings Inc.</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>82968B103</cusip>
			<value>1435</value>
			<shrsOrPrnAmt>
				<sshPrnamt>384592</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>384592</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Valeant Pharmaceuticals</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>91911K102</cusip>
			<value>3927</value>
			<shrsOrPrnAmt>
				<sshPrnamt>17678</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>17678</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Viacom</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>92553P201</cusip>
			<value>1351</value>
			<shrsOrPrnAmt>
				<sshPrnamt>20823</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>20823</None>
			</votingAuthority>
		</infoTable>
</informationTable>
