1. TWI, http://www.twi.co.uk/.
2. Malarvizh S., V. Balasubramanian. (2012), Influences of tool shoulder diameter to plate thickness ratio (D/T) on stir zone formation and tensile properties of friction stir welded dissimilar joints of AA6061 aluminium–AZ31B magnesium alloys, Materials and Design, 40, p. 453-460.
3. Buffa, G., Donati, L., Fratini, L., Tomesani, L. (2006), Solid state bonding in extrusion and FSW: Process mechanics and analogies, Journal of Materials Processing Technology, 177, 1-3, p. 344-347.
4. Ceretti, E., Fratini, L., Gagliardi, F., Giardini, C. (2009), A new approach to study material bonding in extrusion porthole dies, CIRP Annals - Manufacturing Technology, 58, 1, p. 259-262.
5. Audi (2013), Audi Space Frame, text and pictures available at: http://www.audi.co.uk/new-cars/a8/a8/safety/audi-space- frame.html.