Ratcliffe B. Economy and efficiency in transport and distribution / B.Ratcliffe, 1987. - 170 p. - Текст : непосредственный.
Ratcliffe C. Doubt-Free Uncertainty In Measurement : An Introduction for Engineers and Students / C. Ratcliffe, B. Ratcliffe, 2015 r=on-line. - Текст : электронный.