1. P. Dong, J.L. Chen: Chinese Journal of Aerospace Manufacturing Technology, Vol. 1(2014), p.1.
2. X.Y. Gong, M.K. Liu, Y. Li: Chinese Journal of Laser, Vol. 39(2012), p.1.
3. Information on http: /www. 360doc. com/content/14/0415/16/15484603_369211863. shtml.
4. Information on http: /www. stratasys. com. cn/3d-printers/design-series.