The R package copula can be cited (after updating the year and package version) via:
@Manual{,
title = {copula: Multivariate Dependence with Copulas},
author = {Marius Hofert and Ivan Kojadinovic and Martin Maechler and Jun Yan},
year = {2016},
note = {R package version 0.999-15},
url = {http://cran.r-project.org/package=copula}
}
The book can be cited via:
@Book{,
title = {{E}lements of {C}opula {M}odeling with \textsf{R}},
year = 2018,
publisher = {Springer Use R! Series},
isbn = {978-3-319-89635-9},
url = {http://www.springer.com/de/book/9783319896342},
author = {Marius Hofert and Ivan Kojadinovic and Martin Maechler and Jun Yan},
}