We've benefited from a number of resources when writing the package.
The plm package by Croissant and Millo (2008-2019) was an inspiration.
Additionally, a number of books, blogs, and forum entries on
stackexchange proved to be very resourceful. A notable example is the
book R Packages by Hadley Wickham and Jennifer Bryan.

We thank several researchers for the permission to include datasets
in the package:
Manuel Arellano and Steve Bond for the dataset on employment of
firms located in the UK.
James H. Stock and Mark W. Watson for the dataset on cigarette
consumption in the US provided to them by Jonathan Gruber of the
Massachusetts Institute of Technology.

