Added references to other notebooks

Author: jo-mueller

05_feature_extraction/05_feature_extraction_and_thresholds.ipynb

@@ -49,7 +49,7 @@
    "id": "9e77ab67-e3a7-4b95-adde-073f6e98c5e3",
    "metadata": {},
    "source": [
-    "The next cell shows how to combine multiple curves/plots in a single figure. \n",
+    "The next cell shows how to combine multiple curves/plots in a single figure. For a bit more information, see [this notebook](./00_plotting_in_python.ipynb). \n",
     "\n",
     "*Optional:* Change the value for `bins` to see what effect it has on the plotted histogram:"
    ]
@@ -284,7 +284,7 @@
    "source": [
     "## Exercise 4\n",
     "\n",
-    "In the lecture, you learned how to measure *roundness* and *circularity* of objects. Neither of these is available through `regionprops_table`, so we have to calculate them ourselves. They are defined as following:\n",
+    "In the [lecture](./Feature_extraction.pdf), you learned how to measure *roundness* and *circularity* of objects. Neither of these is available through `regionprops_table`, so we have to calculate them ourselves. They are defined as following:\n",
     "\n",
     "- *Roundness* = $\\frac{4 \\cdot A}{\\pi \\cdot \\text{major}}$, where `major` and `A` correspond to the major axis of the ellipse fitted to the object and the object's area\n",
     "- *Circularity* = $\\frac{4 \\cdot \\pi A}{perimeter^2}$\n",