^McConnell, Campbell; Brue, Stanley; Flynn, Sean (2009). Economics. Boston: Twayne Publishers. s. G-22. ISBN978-0-07-337569-4.
^Gregory and Stuart, Paul and Robert (28 Şubat 2013). The Global Economy and its Economic Systems. South-Western College Pub. s. 30. ISBN978-1285055350. There are three broad forms of property ownership – private, public, and collective (cooperative).
^Bertrand Badie; Dirk Berg-Schlosser; Leonardo Morlino (2011). International Encyclopedia of Political Science. SAGE Publications, Inc. s. 2132. ISBN978-1412959636. Private property cannot exist without a political system that defines its existence, its use, and the conditions of its exchange. That is, private property is defined and exists only because of politics.