H. Ehrich, R. Jungclaus, G. Denker, and A. Sernadas. CISM - Advances in Database Systems, volume 347 of CISM International Centre for Mechanical Sciences - Courses and Lectures, page 201-218. Springer, (1993)
G. Saake, T. Hartmann, R. Jungclaus, and H. Ehrich. CISM - Advances in Database Systems, volume 347 of CISM International Centre for Mechanical Sciences - Courses and Lectures, page 219-245. Springer, (1993)