@article{Pennycuick-1996-4774,
  author = {Pennycuick, C},
  title = {Wingbeat Frequency of Birds in Steady Cruising Flight: New Data and Improved Predictions},
  journal = {Journal of Experimental Biology},
  year = {1996},
  month = {mar},
  publisher = {The Company of Biologists},
  volume = {199},
  pages = {1613--1618},
  doi = {10.1242/jeb.199.7.1613},
  url = {http://jeb.biologists.org/content/199/7/1613},
  keywords = {Birds},
}