Boyes, John; Russell, Ronald (1977): . David and Charles. ISBN 978-0-7153-7415-3. Priestley, Joseph (1831): . Skempton, Alec et. al. (2002): . Thomas Telford. ISBN 0-7277-2939-X. Squires, Roger (2008): . Landmark Publishing. ISBN 978-1-84306-331-5.