where
(14.11.1) holds if is replaced by , provided that the factor in (14.11.3) is replaced by . (14.11.4) holds if , , and are replaced by , , and , respectively.
See also Szmytkowski (2006, 2009, 2011, 2012), Cohl (2010, 2011) and Magnus et al. (1966, pp. 177–178).