T. Zimmermann, and P. Weißgerber. Proc. Int'l Workshop on Mining Software Repositories (MSR), page 2-6. Los Alamitos CA, IEEE Computer Society Press, (2004)
M. Lehman, and J. Ramil. Proc. Int'l Workshop on Principles of Software Evolution (IWPSE), page 2--11. IEEE Computer Society Press, (November 2000)Kanazawa, Japan.