[paper][biblio] add missing dois

paper.bib

@@ -26,7 +26,8 @@
   volume    = {81},
   pages     = {64--77},
   year      = {2015},
-  publisher = {Elsevier}
+  publisher = {Elsevier},
+  Doi       = {doi.org/10.1016/j.cageo.2015.04.012},
 }
 
 @article{zhang2015finite,
@@ -36,7 +37,8 @@
   volume    = {529},
   pages     = {890--908},
   year      = {2015},
-  publisher = {Elsevier}
+  publisher = {Elsevier},
+  Doi       = {doi.org/10.1016/j.jhydrol.2015.08.065},
 }
 
 @article{lee2019stochastic,
@@ -47,7 +49,8 @@
   number     = {1},
   pages      = {19--34},
   year       = {2019},
-  publisher  = {Copernicus GmbH}
+  publisher  = {Copernicus GmbH},
+  Doi        = {10.5194/hess-23-19-2019},
 }
 
 @article{alghalandis2017,
@@ -104,6 +107,7 @@ keywords = "Fracture networks, DFN, Stochastic modeling, Open source, Matlab, Fl
   number    = {1},
   pages     = {5},
   publisher = {Springer},
+  Doi       = {doi.org/10.1007/s13137-019-0116-8},
 }
 
 @TechReport{keilegavlen2017,
@@ -129,11 +133,18 @@ keywords = "Fracture networks, DFN, Stochastic modeling, Open source, Matlab, Fl
   publisher = {John Wiley \& Sons, Ltd.},
 }
 
-@Article{berge2019,
-  author  = {Berge, Runar L and Berre, Inga and Keilegavlen, Eirik and Nordbotten, Jan M and Wohlmuth, Barbara},
-  title   = {Finite volume discretization for poroelastic media with fractures modeled by contact mechanics},
-  journal = {arXiv preprint arXiv:1904.11916},
-  year    = {2019},
+@article{berge2019,
+author = {Berge, Runar L. and Berre, Inga and Keilegavlen, Eirik and Nordbotten, Jan M. and Wohlmuth, Barbara},
+title = {Finite volume discretization for poroelastic media with fractures modeled by contact mechanics},
+journal = {International Journal for Numerical Methods in Engineering},
+volume = {121},
+number = {4},
+pages = {644-663},
+keywords = {Biot, contact mechanics, finite volume, fractures},
+doi = {10.1002/nme.6238},
+url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/nme.6238},
+eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1002/nme.6238},
+year = {2020}
 }
 
 @Article{Flemisch2018Benchmarks,
@@ -156,7 +167,7 @@ keywords = "Fracture networks, DFN, Stochastic modeling, Open source, Matlab, Fl
   volume   = {183},
   pages    = {106350},
   issn     = {0920-4105},
-  doi      = {https://doi.org/10.1016/j.petrol.2019.106350},
+  doi      = {doi.org/10.1016/j.petrol.2019.106350},
   keywords = {Discrete fracture modeling, Improved oil recovery, Recovery optimization},
 }
 
@@ -197,6 +208,7 @@ keywords = "Fracture networks, DFN, Stochastic modeling, Open source, Matlab, Fl
   number    = {1},
   pages     = {7},
   publisher = {Springer},
+  Doi       = {doi.org/10.1007/s13137-019-0117-7},
 }
 
 @Article{schadle2019,
@@ -220,6 +232,7 @@ keywords = "Fracture networks, DFN, Stochastic modeling, Open source, Matlab, Fl
   number    = {2},
   pages     = {225--237},
   publisher = {Springer},
+  Doi       = {doi.org/10.1007/s10596-018-9778-9},
 }
 
 @Article{brenner2018,
@@ -244,6 +257,7 @@ keywords = "Fracture networks, DFN, Stochastic modeling, Open source, Matlab, Fl
   number    = {8},
   pages     = {3053--3065},
   publisher = {Springer},
+  Doi       = {doi.org/10.1007/s12665-014-3211-z},
 }
 
 @Article{torabi2012,
@@ -254,6 +268,7 @@ keywords = "Fracture networks, DFN, Stochastic modeling, Open source, Matlab, Fl
   volume    = {93},
   pages     = {443--453},
   publisher = {Elsevier},
+  Doi       = {doi.org/10.1016/j.fuel.2011.08.037},
 }
 
 @TechReport{mcfarland1976,