This should prove helpful:
@ARTICLE{machlup_penrose50jehist,
author = {Machlup, Fritz and Edith Penrose},
year = 1950,
title = {The Patent Controversy in the Nineteenth Century},
journal = {Journal of Economic History},
volume = 10,
number = 1,
month = may,
pages = {1--29}
}
hth,
Alan Isaac