diff --git a/map/gps/gps-chase.html b/map/gps/gps-chase.html
index a7d0328..b0ee2a4 100644
--- a/map/gps/gps-chase.html
+++ b/map/gps/gps-chase.html
@@ -43,6 +43,7 @@
 
 <div class="a">
 <h2>References</h2>
+<ul><p>https://www.koeki-prj.org/~yuuji/2021/gd2/index.html</p></ul>
 <ul><p>https://developer.mozilla.org/ja/docs/Web/HTML/Element/video</p></ul>
 <ul><p>https://www.nanchatte.com/l/showMapWithMarkerAndInfoWindow.html</p></ul>
 <ul><p>https://user.numazu-ct.ac.jp/~tsato/webmap/sphere/coordinates/advanced.html</p></ul>