=+Variation in Forming of High Strength Steels” (J. of Manuf. Sci. and Engr., 2008: 1–9) included data on y 5 springback from the wall opening angle and x 5 blank holder pressure (BHP). Three different material suppliers and three different lubrication regimens (no lubrication, lubricant 1, and lubricant 2) were also utilized.