From the Steam store page.
Screenshots originally available at http://www.bitmap-brothers.co.uk/zss.html
Screenshots originally published in a preview pack at the Bitmap Brothers website, but not found in the screenshot gallery. The most recent image file is dated January 17, 1996.
Images originally available at: http://www.vie.com/z/index.html (pages archived by the Wayback Machine).
Images available, as of December 2016, at: http://www.bitmap-brothers.co.uk/downloads/images/z/index.htm
Images published on the on the cover CD of the Czech gaming magazine SCORE (issue No. 21, September 1995). The date stamps on the files are from 12 September 1995.
Images originally available at: http://www.virgininteractive.fr/html/lesjeux/strategie/z/z.html (page archived by the Wayback Machine).