Yares, Evan (February 17, 2012). "AutoCAD's ancestor". 3D CAD World. AutoCAD's ancestor: WTWH Media, LLC. Archived from the original on February 1, 2014. Retrieved November 21, 2022.
Yares, Evan (February 17, 2012). "AutoCAD's ancestor". 3D CAD World. AutoCAD's ancestor: WTWH Media, LLC. Archived from the original on February 1, 2014. Retrieved November 21, 2022.