1. International tennis federation (2017) ITF technical FAQs.
http://www.itftennis.com/technical/technical-centre/faqs/faqs.aspx
. Accessed 19 Jan 2017
2. statista (2017) Wholesale sales of tennis equipment in the US. 2007–2015.
https://www.statista.com/statistics/258666/tennis-equipment-wholesale-sales-in-the-us/
. Accessed 01 Feb 2017
3. ITF (2016) Approved balls 2016.
http://www.itftennis.com/technical/balls/approved-balls.aspx
. Accessed 22 Feb 2016
4. ITF (2015) ITF Approved tennis balls, classified surfaces & recognised courts a guide to products & test methods. ITF Licensing (UK) Ltd, Roehampton, UK
5. Steele C, Jones R, Leaney P (2006) Factors in tennis ball wear. In: Moritz E, Haake S (eds) English sport 6. Springer, New York, pp 361–366