diff --git a/usingPictureMarkup/external/matchMedia.js b/usingPictureMarkup/external/matchMedia.js
deleted file mode 100755
index 0bfca11..0000000
--- a/usingPictureMarkup/external/matchMedia.js
+++ /dev/null
@@ -1,46 +0,0 @@
-/*! matchMedia() polyfill - Test a CSS media type/query in JS. Authors & copyright (c) 2012: Scott Jehl, Paul Irish, Nicholas Zakas, David Knight. Dual MIT/BSD license */
-
-window.matchMedia || (window.matchMedia = function() {
-    "use strict";
-
-    // For browsers that support matchMedium api such as IE 9 and webkit
-    var styleMedia = (window.styleMedia || window.media);
-
-    // For those that don't support matchMedium
-    if (!styleMedia) {
-        var style       = document.createElement('style'),
-            script      = document.getElementsByTagName('script')[0],
-            info        = null;
-
-        style.type  = 'text/css';
-        style.id    = 'matchmediajs-test';
-
-        script.parentNode.insertBefore(style, script);
-
-        // 'style.currentStyle' is used by IE <= 8 and 'window.getComputedStyle' for all other browsers
-        info = ('getComputedStyle' in window) && window.getComputedStyle(style, null) || style.currentStyle;
-
-        styleMedia = {
-            matchMedium: function(media) {
-                var text = '@media ' + media + '{ #matchmediajs-test { width: 1px; } }';
-
-                // 'style.styleSheet' is used by IE <= 8 and 'style.textContent' for all other browsers
-                if (style.styleSheet) {
-                    style.styleSheet.cssText = text;
-                } else {
-                    style.textContent = text;
-                }
-
-                // Test if media query is true or false
-                return info.width === '1px';
-            }
-        };
-    }
-
-    return function(media) {
-        return {
-            matches: styleMedia.matchMedium(media || 'all'),
-            media: media || 'all'
-        };
-    };
-}());