@article{GDZPPN00218379X,
title = {Exponentiation of functions in MacLane's class A.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {238},
year = {1969},
pages = {120-130},
zbl = {0175.07801},
url = {http://dml.mathdoc.fr/item/GDZPPN00218379X}
}
Barth, K.F.; Schneider, W.J. Exponentiation of functions in MacLane's class A.. Journal für die reine und angewandte Mathematik, Tome 238 (1969) pp. 120-130. http://gdmltest.u-ga.fr/item/GDZPPN00218379X/