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?
Ludwig von Mises: Ludwig Heinrich Edler von Mises ( ; ] ; 29 September 1881 – 10 October 1973) was an Austrian-American theoretical Austrian School economist. Ludwig von Mises:  He is best known for his work on praxeology, a study of human choice and action.
i don't know