add scaper ref

Author: justinsalamon

book/data/scaper.ipynb

@@ -58,6 +58,22 @@
     "<img src=\"https://www.justinsalamon.com/uploads/4/3/9/4/4394963/scaper-diagram_orig.png\">"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Read more\n",
+    "\n",
+    "You can learn more about Scaper by reading the scaper-paper:\n",
+    "\n",
+    "\n",
+    "[Scaper: A library for soundscape synthesis and augmentation](http://www.justinsalamon.com/uploads/4/3/9/4/4394963/salamon_scaper_waspaa_2017.pdf)<br/>\n",
+    "J. Salamon, D. MacConnell, M. Cartwright, P. Li, and J. P. Bello<br/>\n",
+    "In IEEE Workshop on Applications of Signal Processing to Audio and Acoustics (WASPAA), New Paltz, NY, USA, Oct. 2017.\n",
+    "\n",
+    "Please cite this paper if you use Scaper in your work. You do not need to read the paper to complete this tutorial."
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},