diff --git a/README.Rmd b/README.Rmd
index 0797d18..d9b31e2 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -18,7 +18,8 @@ knitr::opts_chunk$set(
 # About `{aca.medicaid.expansion}`
 
 The package `{aca.medicaid.expansion}` contains a dataset `status`, which 
-includes the status of state action on the ACA Medicaid expansion decision.
+includes the status of state action on the ACA Medicaid expansion decision. 
+The first version of the data is from [the Kaiser Family Foundation](https://www.kff.org/medicaid/issue-brief/status-of-state-medicaid-expansion-decisions-interactive-map/).
 
 # Installation
 
diff --git a/README.md b/README.md
index c9f1250..a859293 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,8 @@
 
 The package `{aca.medicaid.expansion}` contains a dataset `status`,
 which includes the status of state action on the ACA Medicaid expansion
-decision.
+decision. The first version of the data is from [the Kaiser Family
+Foundation](https://www.kff.org/medicaid/issue-brief/status-of-state-medicaid-expansion-decisions-interactive-map/).
 
 # Installation
 
diff --git a/docs/index.html b/docs/index.html
index debb89b..8b6e2ca 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -77,7 +77,7 @@
 <div class="page-header"><h1 class="hasAnchor">
 <a href="#about-aca-medicaid-expansion" class="anchor"></a>About <code>{aca.medicaid.expansion}</code>
 </h1></div>
-<p>The package <code>{aca.medicaid.expansion}</code> contains a dataset <code>status</code>, which includes the status of state action on the ACA Medicaid expansion decision.</p>
+<p>The package <code>{aca.medicaid.expansion}</code> contains a dataset <code>status</code>, which includes the status of state action on the ACA Medicaid expansion decision. The first version of the data is from <a href="https://www.kff.org/medicaid/issue-brief/status-of-state-medicaid-expansion-decisions-interactive-map/">the Kaiser Family Foundation</a>.</p>
 </div>
 <div id="installation" class="section level1">
 <h1 class="hasAnchor">