<informationTable xmlns="http://www.sec.gov/edgar/document/thirteenf/informationtable">		<infoTable>
			<nameOfIssuer>Aspen Aerogels</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>04523Y105</cusip>
			<value>19226</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>348371</value>
			<shrsOrPrnAmt>
				<sshPrnamt>5826570</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>SOLE</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>5826570</Sole>
				<Shared>0</Shared>
				<None>0</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Cognizant Technology Solutions</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>192446102</cusip>
			<value>4502</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>Calpine Corporation</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>131347304</cusip>
			<value>2435</value>
			<shrsOrPrnAmt>
				<sshPrnamt>168292</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>168292</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Cimpress</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>N20146101</cusip>
			<value>1345</value>
			<shrsOrPrnAmt>
				<sshPrnamt>16573</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>16573</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Express Scripts</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>30219G108</cusip>
			<value>1026</value>
			<shrsOrPrnAmt>
				<sshPrnamt>11741</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>11741</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>JPMorgan Chase &amp; Co</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>46625H100</cusip>
			<value>2729</value>
			<shrsOrPrnAmt>
				<sshPrnamt>41334</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>41334</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Liberty Broadband Corp</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>530307305</cusip>
			<value>3445</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>1821</value>
			<shrsOrPrnAmt>
				<sshPrnamt>44674</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>44674</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Liberty Global - USD0.01A</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>G5480U104</cusip>
			<value>650</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>Liberty Lilac Group - Series C</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>G5480U153</cusip>
			<value>224</value>
			<shrsOrPrnAmt>
				<sshPrnamt>5204</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>5204</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Live Nation Entertainment Inc.</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>538034109</cusip>
			<value>547</value>
			<shrsOrPrnAmt>
				<sshPrnamt>22271</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>22271</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Mastercard CL A</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>57636Q104</cusip>
			<value>869</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>4234</value>
			<shrsOrPrnAmt>
				<sshPrnamt>76315</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>76315</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Sirius XM Holdings Inc.</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>82968B103</cusip>
			<value>1174</value>
			<shrsOrPrnAmt>
				<sshPrnamt>288444</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>288444</None>
			</votingAuthority>
		</infoTable>
		<infoTable>
			<nameOfIssuer>Valeant Pharmaceuticals</nameOfIssuer>
			<titleOfClass>Common</titleOfClass>
			<cusip>91911K102</cusip>
			<value>2987</value>
			<shrsOrPrnAmt>
				<sshPrnamt>29382</sshPrnamt>
				<sshPrnamtType>SH</sshPrnamtType>
			</shrsOrPrnAmt>
			<investmentDiscretion>OTR</investmentDiscretion>
			<otherManager>n/a</otherManager>
			<votingAuthority>
				<Sole>0</Sole>
				<Shared>0</Shared>
				<None>29382</None>
			</votingAuthority>
		</infoTable>
</informationTable>
