*Caralle, Katelyn (September 1, 2017). [http://freebeacon.com/politics/obama-most-costly-former-president-2018/ Obama Poised to Be Most Costly Former President in 2018]. ''The Washington Free Beacon''. Retrieved September 2, 2017. | *Caralle, Katelyn (September 1, 2017). [http://freebeacon.com/politics/obama-most-costly-former-president-2018/ Obama Poised to Be Most Costly Former President in 2018]. ''The Washington Free Beacon''. Retrieved September 2, 2017. |