1. Historical origins of indentation hardness testing
2. de RéaumurRA‘L’art de convertir le fer forgé en acier et l’art d’acoucir le fer fondu’; 1722, Paris, France, Michel Brunet (for a translation into English, see A. G. Sisco and C. S. Smith: ‘Réaumur’s memoirs on steel and iron’; 1956, Chicago, IL, The University of Chicago Press).