Question: Hans F. Sennholz was a prolific author who studied under a theoretical Austrian School economist best known for his work on praxeology, a study of what?

Context paragraphs:
America's Great Depression: America's Great Depression is a 1963 treatise on the 1930s Great Depression and its root causes, written by Austrian School economist and author Murray Rothbard.  The fifth edition was released in 2000.

Bureaucracy (book): Bureaucracy is a political book written by Austrian School economist and libertarian thinker Ludwig von Mises.  The author's stated motivation in writing the book is his concern with the spread of socialist ideals and the increasing bureaucratization of economic life.  While he does not deny the necessity of certain bureaucratic structures for the smooth operation of any civilized state, he disagrees with the extent to which it has come to dominate the public life of European countries and the United States.  The author's purpose is to demonstrate that the negative aspects of bureaucracy are not a result of bad policies or corruption as the public tends to think but are necessarily built into bureaucratic structures due to the very tasks these structures have to deal with.  The main body of the book is therefore devoted to a comparison between private enterprise on the one hand and bureaucratic agencies/public enterprise on the other.

Frank Shostak: Frank Shostak is an Austrian School economist.  He is an adjunct scholar of the Mises Institute.  His Consulting firm, Applied Austrian School Economics, provides in-depth assessments and reports of financial markets and global economies.

Socialism (book): Socialism: An Economic and Sociological Analysis is a book by Austrian School economist and libertarian thinker Ludwig von Mises, first published in German by in Jena in 1922 under the title "Die Gemeinwirtschaft: Untersuchungen über den Sozialismus".  It was translated into English from the second reworked German edition (Jena: Gustav Fischer Verlag, 1932) by J. Kahane and published by Jonathan Cape in London in 1936.  In 1951 the translation was reworked with the assistance of the author and published by Yale University Press in New Haven with the addition of an epilogue by Mises, originally published in 1947 as "Planned Chaos" by the Foundation for Economic Education (Irvington, NY).

Hans Sennholz: Hans F. Sennholz ( ; ] ; 3 February 1922 – 23 June 2007) was a German-born American Austrian School economist and prolific author who studied under Ludwig von Mises.  A Luftwaffe pilot during World War II, he was shot down over North Africa on 31 August 1942, and spent the remainder of the war in a POW camp in the United States.

Peter G. Klein: Peter G. Klein is an American Austrian School economist who studies managerial and organizational issues.  Klein is professor of entrepreneurship at Baylor University’s Hankamer School of Business and senior research fellow at the Baugh Center for Entrepreneurship and Free Enterprise.  He came to Baylor from the University of Missouri, where he was professor of applied social sciences and professor of public affairs.  Klein is also adjunct professor of strategy and management at the Norwegian School of Economics and Business Administration and Carl Menger Research Fellow at the Mises Institute.  He serves as field editor for the "Journal of Business Venturing", associate editor of the "Academy of Management Perspectives", and associate editor of "The Independent Review".  His 2012 book "Organizing Entrepreneurial Judgment" (with Nicolai Foss, Cambridge University Press) won the 2014 Foundation for Economic Education Best Book Prize, and his 2010 book "The Capitalist and the Entrepreneur" (Mises Institute) has been translated into Chinese and Portuguese.  He holds an honorary professorship at the Beijing University of Information Science and Technology.

Walter Block: Walter Edward Block (born August 21, 1941) is an American Austrian School economist and anarcho-capitalist theorist.  He currently holds the Harold E. Wirth Eminent Scholar Endowed Chair in Economics at the J. A. Butt School of Business at Loyola University New Orleans.  He is a senior fellow of the Ludwig von Mises Institute in Auburn, Alabama.  He is best known for his 1976 book "Defending the Undefendable", which takes contrarian positions in defending acts which are illegal or disreputable but Block argues are actually victimless crimes or benefit the public.

Ludwig von Mises: Ludwig Heinrich Edler von Mises ( ; ] ; 29 September 1881 – 10 October 1973) was an Austrian-American theoretical Austrian School economist.  Mises wrote and lectured extensively on behalf of classical liberalism.  He is best known for his work on praxeology, a study of human choice and action.

Joseph Salerno: Joseph T. Salerno (born 1950) is an American Austrian School economist who is Professor of Economics, Chair of the economics graduate program in the Lubin School of Business at Pace University, and Academic Vice President of the Ludwig von Mises Institute.  He earned his B.A. at Boston College and his M.A. and Ph.D. at Rutgers University.

Ludwig von Mises Institute: The Ludwig von Mises Institute (LvMI), often referred to as the Mises Institute, is a tax-exempt organization located in Auburn, Alabama, United States.  It is named after Austrian School economist Ludwig von Mises (1881–1973).  Its website states that it exists to promote "teaching and research in the Austrian school of economics, and individual freedom, honest history, and international peace, in the tradition of Ludwig von Mises and Murray N. Rothbard."

Supporting paragraphs: Hans Sennholz Ludwig von Mises
Answer: human choice and action