(A SYSTEM OF LOGIC,RATIOCINATIVE AND INDUCTIVE,BEING A CONNECTED VIEW OF THE PRINCIPLES OF EVIDENCE, AND THE METHODS OF SCIENTIFIC INVESTIGATION. by JOHN STUART MILL. 8th Edition.New York:Harper & Brothers, Publishers,Franklin Square.1882.Chapter VIII. Of The Four Methods Of Experimental Inquiry.)http://www.gutenberg.org/files/27942/27942-h/27942-h.html