When using pwt8 in publications, please cite both the pwt8 package and the Penn World Table itself:

To cite pwt8, the R package, please use:

Achim Zeileis (2017). pwt8: Penn World Table (Version 8.x). R package version 8.1-1. URL https://CRAN.R-project.org/package=pwt8.

To cite the Penn World Table (version 8.x), please use:

Robert C. Feenstra, Robert Inklaar, Marcel P. Timmer (2015). The Next Generation of the Penn World Table. American Economic Review, 105(10), 3150-3182. URL http://www.ggdc.net/pwt/.

Corresponding BibTeX entries:

    title = {pwt8: Penn World Table (Version 8.x)},
    author = {Achim Zeileis},
    year = {2017},
    note = {R package version 8.1-1},
    url = {https://CRAN.R-project.org/package=pwt8},
    title = {The Next Generation of the Penn World Table},
    author = {Robert C. Feenstra and Robert Inklaar and Marcel P.
    year = {2015},
    journal = {American Economic Review},
    volume = {105},
    number = {10},
    pages = {3150--3182},
    url = {http://www.ggdc.net/pwt/},