Chemical Hardness. R. G. Pearson

Hard and Soft Acids and Bases—the Evolution of a Chemical Concept , R. G. Pearson, Coord. Chem. Rev. (1990), 100, 403. 

R. G. Pearson, Chemical Hardness, Wiley-VCH, Weinheim, Germany (1997). 

J. Maruani, A. Khondir and M. Tronc, Progr. Theor. Chem. Phys. B3 (2000) 123. R. G. Pearson, Chemical Hardness (Wiley, New York, 1997). 

R.G. Pearson (1997) Chemical Hardness, Wiley-VCH, Weinheim - By the originator of the theory of chemical hardness, this book provides an account of its applications in chemistry. 

Pearson, R. G. (1963). Hard and soft acids and bases. Journal of the American Chemical Society, 85, 3533-9. 

---