diff --git a/README.Rmd b/README.Rmd
index d4a2422..a0435b2 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -104,6 +104,8 @@ Use `npi_is_valid()` to check whether each element of a vector of candidate numb
 npi_is_valid(c(1234567893, 1234567898))
 ```
 
+This function doesn't check whether the NPI numbers are activated or deactivated (see https://github.com/frankfarach/npi/issues/22#issuecomment-787642817).
+
 ## Set your own user agent
 
 By default, all request headers include a user agent that references this repository. You can customize the user agent by setting the `npi_user_agent` option:
@@ -128,6 +130,10 @@ Please note that this project is released with a [Contributor Code of Conduct](C
 
 Interested in learning how you can contribute to npi? Head over to the [contributor guide](CONTRIBUTING.md)—and thanks for considering!
 
+## How to cite this package
+
+For the latest citation, see the [Authors and Citation](https://frankfarach.github.io/npi/authors.html#citation) page on the package website. 
+
 ## License
 
 MIT (c) [Frank Farach](https://github.com/frankfarach)
diff --git a/README.md b/README.md
index e2ac893..1fc324b 100644
--- a/README.md
+++ b/README.md
@@ -199,6 +199,10 @@ npi_is_valid(c(1234567893, 1234567898))
 #> [1] TRUE
 ```
 
+This function doesn’t check whether the NPI numbers are activated or
+deactivated (see
+<https://github.com/frankfarach/npi/issues/22#issuecomment-787642817>).
+
 ## Set your own user agent
 
 By default, all request headers include a user agent that references
@@ -231,6 +235,12 @@ to abide by its terms.
 Interested in learning how you can contribute to npi? Head over to the
 [contributor guide](CONTRIBUTING.md)—and thanks for considering!
 
+## How to cite this package
+
+For the latest citation, see the [Authors and
+Citation](https://frankfarach.github.io/npi/authors.html#citation) page
+on the package website.
+
 ## License
 
 MIT (c) [Frank Farach](https://github.com/frankfarach)