docs(block-encoding): fix nbstripout normalization

Author: virajd98

applications/block_encoding/select_structures_BE.ipynb

@@ -1330,6 +1330,24 @@
    "source": [
     "____"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "27",
+   "metadata": {},
+   "source": [
+    "### Reference\n",
+    "\n",
+    "- Sunderhauf, C., Campbell, E., Camps, J.: Block-encoding structured matrices fordata input in quantum computing. Quantum 8, 1226 (2024) https://doi.org/10.22331/q-2024-01-11-1226."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "28",
+   "metadata": {},
+   "source": [
+    "___"
+   ]
   }
  ],
  "metadata": {