diff --git a/DESCRIPTION b/DESCRIPTION
index 8be381f..0597967 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -2,7 +2,7 @@ Package: DirStats
 Type: Package
 Title: Nonparametric Methods for Directional Data
 Version: 0.1.7
-Date: 2020-09-07
+Date: 2021-01-09
 Authors@R: person(given = "Eduardo", family = "García-Portugués",
                   role = c("aut", "cre"), email = "edgarcia@est-econ.uc3m.es",
                   comment = c(ORCID = "0000-0002-9224-4111"))
diff --git a/R/bw-cv.R b/R/bw-cv.R
index cff1b80..027bfca 100644
--- a/R/bw-cv.R
+++ b/R/bw-cv.R
@@ -41,11 +41,11 @@
 #' @references
 #' Cody, W. J. (1983). Algorithm 597: Sequence of modified Bessel functions of
 #' the first kind. \emph{ACM Transactions on Mathematical Software},
-#' 9(2):242--245. \url{https://doi.org/10.1145/357456.357462}
+#' 9(2):242--245. \doi{10.1145/357456.357462}
 #'
 #' Hall, P., Watson, G. S., and Cabrera, J. (1987). Kernel density estimation
 #' with spherical data. \emph{Biometrika}, 74(4):751--762.
-#' \url{https://doi.org/10.1093/biomet/74.4.751}
+#' \doi{10.1093/biomet/74.4.751}
 #'
 #' Sookne, D. J. (1973). Bessel functions of real argument and integer order.
 #' \emph{Journal of Research of the National Bureau of Standards},
diff --git a/R/bw-pi.R b/R/bw-pi.R
index 919b082..d1741fd 100644
--- a/R/bw-pi.R
+++ b/R/bw-pi.R
@@ -37,11 +37,11 @@
 #' García-Portugués, E. (2013). Exact risk improvement of bandwidth selectors
 #' for kernel density estimation with directional data. \emph{Electronic
 #' Journal of Statistics}, 7:1655--1685.
-#' \url{https://doi.org/10.1214/13-ejs821}
+#' \doi{10.1214/13-ejs821}
 #'
 #' Hornik, K. and Grün, B. (2014). movMF: An R Package for Fitting Mixtures of
 #' von Mises--Fisher Distributions. \emph{Journal of Statistical Software},
-#' 58(10):1--31. \url{https://doi.org/10.18637/jss.v058.i10}
+#' 58(10):1--31. \doi{10.18637/jss.v058.i10}
 #' @examples
 #' # Sample
 #' q <- 2
@@ -260,7 +260,7 @@ bic_vmf_mix <- function(data, M_bound = ceiling(log(nrow(data))), M_neig = 3,
 #' García-Portugués, E. (2013). Exact risk improvement of bandwidth selectors
 #' for kernel density estimation with directional data. \emph{Electronic
 #' Journal of Statistics}, 7:1655--1685.
-#' \url{https://doi.org/10.1214/13-ejs821}
+#' \doi{10.1214/13-ejs821}
 #' @examples
 #' # Sample
 #' n <- 25
diff --git a/R/kde.R b/R/kde.R
index 2f38854..7de3e4f 100644
--- a/R/kde.R
+++ b/R/kde.R
@@ -23,7 +23,7 @@
 #' Bai, Z. D., Rao, C. R., and Zhao, L. C. (1988). Kernel estimators of
 #' density function of directional data. \emph{Journal of Multivariate
 #' Analysis}, 27(1):24--39.
-#' \url{https://doi.org/10.1016/0047-259X(88)90113-3}
+#' \doi{10.1016/0047-259X(88)90113-3}
 #' @examples
 #' # Sample
 #' n <- 50
diff --git a/cran-comments.md b/cran-comments.md
index 865538f..9eef8c8 100644
--- a/cran-comments.md
+++ b/cran-comments.md
@@ -1,6 +1,6 @@
 ## Test environments
 
-* local R installation, R 3.6.3
+* local R installation, R 4.0.3
 * ubuntu 16.04 (on travis-ci), R 3.6.3
 * win-builder (release, devel)
 * Windows Server 2008 R2 SP1, R-devel, 32/64 bit (on R-hub)
@@ -14,6 +14,4 @@
 
 ## R CMD check results
 
-0 errors | 0 warnings | 1 note
-
-* "Days since last update: 1" I am resubmitting to fix the error in https://www.r-project.org/nosvn/R.check/r-patched-solaris-x86/DirStats-00check.html Apparently it is fixed in the Oracle Solaris 10 machines of R-hub (see above).
+0 errors | 0 warnings | 0 note
diff --git a/man/bic_vmf_mix.Rd b/man/bic_vmf_mix.Rd
index 6898708..7bc8509 100644
--- a/man/bic_vmf_mix.Rd
+++ b/man/bic_vmf_mix.Rd
@@ -69,9 +69,9 @@ bic_vmf_mix(data = samp, plot_it = TRUE, verbose = TRUE)
 García-Portugués, E. (2013). Exact risk improvement of bandwidth selectors
 for kernel density estimation with directional data. \emph{Electronic
 Journal of Statistics}, 7:1655--1685.
-\url{https://doi.org/10.1214/13-ejs821}
+\doi{10.1214/13-ejs821}
 
 Hornik, K. and Grün, B. (2014). movMF: An R Package for Fitting Mixtures of
 von Mises--Fisher Distributions. \emph{Journal of Statistical Software},
-58(10):1--31. \url{https://doi.org/10.18637/jss.v058.i10}
+58(10):1--31. \doi{10.18637/jss.v058.i10}
 }
diff --git a/man/bw_dir_cv.Rd b/man/bw_dir_cv.Rd
index 13b5e6a..a9d2ed1 100644
--- a/man/bw_dir_cv.Rd
+++ b/man/bw_dir_cv.Rd
@@ -87,11 +87,11 @@ bw_dir_lscv(data = samp, L = function(x) exp(-x))$h_opt
 \references{
 Cody, W. J. (1983). Algorithm 597: Sequence of modified Bessel functions of
 the first kind. \emph{ACM Transactions on Mathematical Software},
-9(2):242--245. \url{https://doi.org/10.1145/357456.357462}
+9(2):242--245. \doi{10.1145/357456.357462}
 
 Hall, P., Watson, G. S., and Cabrera, J. (1987). Kernel density estimation
 with spherical data. \emph{Biometrika}, 74(4):751--762.
-\url{https://doi.org/10.1093/biomet/74.4.751}
+\doi{10.1093/biomet/74.4.751}
 
 Sookne, D. J. (1973). Bessel functions of real argument and integer order.
 \emph{Journal of Research of the National Bureau of Standards},
diff --git a/man/bw_dir_pi.Rd b/man/bw_dir_pi.Rd
index 04e5c4a..0842f0f 100644
--- a/man/bw_dir_pi.Rd
+++ b/man/bw_dir_pi.Rd
@@ -102,5 +102,5 @@ bw_dir_emi(samp, fit_mix = fit_mix, optim = FALSE, plot_it = TRUE)
 García-Portugués, E. (2013). Exact risk improvement of bandwidth selectors
 for kernel density estimation with directional data. \emph{Electronic
 Journal of Statistics}, 7:1655--1685.
-\url{https://doi.org/10.1214/13-ejs821}
+\doi{10.1214/13-ejs821}
 }
diff --git a/man/kde_dir.Rd b/man/kde_dir.Rd
index af164b0..e5eff5c 100644
--- a/man/kde_dir.Rd
+++ b/man/kde_dir.Rd
@@ -78,5 +78,5 @@ lambda_L(L = function(x) exp(-x), q = q)
 Bai, Z. D., Rao, C. R., and Zhao, L. C. (1988). Kernel estimators of
 density function of directional data. \emph{Journal of Multivariate
 Analysis}, 27(1):24--39.
-\url{https://doi.org/10.1016/0047-259X(88)90113-3}
+\doi{10.1016/0047-259X(88)90113-3}
 }