1. World robot population reaches 8.6 million, available from: 〈http://spectrum.ieee.org/automaton/robotics/industrial-robots/041410-world-robot-population〉.
2. Executive summary, available from: http://www.worldrobotics.org/uploads/media/ Executive _ Summary_ WR_2012.pdf.
3. PR2, available from: 〈http://www.willowgarage.com/pages/pr2/overview〉.
4. Care-o-bot 3, available from: 〈http://www.care-o-bot.de/de/care-o-bot-3.html〉.
5. REEM-B, available from: http://pal-robotics.com/robots/reem-b.