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 (2013). pwt8: Penn World Table (Version 8.0). R package version 8.0-0. URL http://CRAN.R-project.org/package=pwt8.

To cite the Penn World Table (version 8.0), please use:

Robert C. Feenstra, Robert Inklaar, Marcel P. Timmer (2013). The Next Generation of the Penn World Table. Groningen Growth and Development Centre. URL http://www.ggdc.net/pwt/.

Corresponding BibTeX entries:

    title = {pwt8: Penn World Table (Version 8.0)},
    author = {Achim Zeileis},
    year = {2013},
    note = {R package version 8.0-0},
    url = {http://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 = {2013},
    month = {July},
    organization = {Groningen Growth and Development Centre},
    url = {http://www.ggdc.net/pwt/},