updated some links (#93)

Author: pat-schmitt

oggm-edu/ice_flow_parameters.ipynb

@@ -92,7 +92,7 @@
    "metadata": {},
    "source": [
     "The parameter relates shear stress to the rate of deformation and is assumed to be constant.\n",
-    "It depends on crystal size, fabric, concentration and type of impurities, as well as on ice temperature [(Oerlemans, 2001)](https://link.springer.com/article/10.1007%2Fs11629-015-3445-6)\n",
+    "It depends on crystal size, fabric, concentration and type of impurities, as well as on ice temperature [(Oerlemans, 2001)](https://doi.org/10.3189/172756502781831557)\n",
     "(you can find a more detailed description of it [here](http://www.antarcticglaciers.org/modern-glaciers/glacier-flow-2/glacier-flow-ii-stress-and-strain/)).\n",
     "\n",
     "Next we will change the creep parameter and see what happens.\n",
@@ -195,7 +195,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Basal sliding occurs when there is a water film between the ice and the ground. In his [seminal paper](https://www.igsoc.org/annals/24/igs_annals_vol24_year1997_pg382-389.pdf), Hans Oerlemans uses a so-called \"sliding parameter\" representing basal sliding.\n",
+    "Basal sliding occurs when there is a water film between the ice and the ground. In his [seminal paper](https://doi.org/10.3189/S0260305500012489), Hans Oerlemans uses a so-called \"sliding parameter\" representing basal sliding.\n",
     "For our glacier this parameter is available under the `.basal_sliding` attribute.\n",
     "By default it is set to 0, but it can be modified"
    ]
@@ -331,7 +331,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.8"
+   "version": "3.10.6"
   },
   "toc": {
    "base_numbering": 1,