Kindle No. 850 > the paragram under Fig.3
Kindle version (typo)
... in sec 3.12. The only difference with plane waves is the replacement of the factor $1/^l$ in the exponent by $1/^l - 1/f$.
printed book (correct)
... in sec 3.12. The only difference with plane waves is the replacement of the factor $1/l$ in the exponent by $1/l - 1/f$.
There are too many mistakes related to the "l" being superscript.