PhaseField docu for energy split models.

Documentation/ProjectFile/prj/processes/process/PHASE_FIELD/t_energy_split_model.md

+Implemented energy split models are:
+- isotropic model \cite bourdin2000numerical, (energy_split_model="Isotropic")
+- volumetric-deviatoric split model \cite amor2009regularized (energy_split_model="VolumetricDeviatoric")

Documentation/bibliography/ogs.bib

@@ -23,16 +23,6 @@
   category={Methods},
 }
 
-@article{tanne2018crack,
-	title={Crack nucleation in variational phase-field models of brittle fracture},
-	author={Tann{\'e}, Erwan and Li, Tianyi and Bourdin, Blaise and Marigo, J-J and Maurini, Corrado},
-	journal={Journal of the Mechanics and Physics of Solids},
-	volume={110},
-	pages={80--99},
-	year={2018},
-	publisher={Elsevier}
-}
-
 @article{Parisio2017,
   title = "Plastic-damage modeling of saturated quasi-brittle shales ",
   journal = "International Journal of Rock Mechanics and Mining Sciences ",

Documentation/bibliography/other.bib

@@ -32,6 +32,39 @@ author = {J. Buchwald and S. Kaiser and O. Kolditz and T. Nagel}
   Publisher={Springer}
 }
 
+@article{tanne2018crack,
+  title={Crack nucleation in variational phase-field models of brittle fracture},
+  author={Tann{\'e}, Erwan and Li, Tianyi and Bourdin, Blaise and Marigo, J-J and Maurini, Corrado},
+  journal={Journal of the Mechanics and Physics of Solids},
+  volume={110},
+  pages={80--99},
+  year={2018},
+  publisher={Elsevier}
+}
+
+@article{bourdin2000numerical,
+  title={Numerical experiments in revisited brittle fracture},
+  author={Bourdin, Blaise and Francfort, Gilles A and Marigo, Jean-Jacques},
+  journal={Journal of the Mechanics and Physics of Solids},
+  volume={48},
+  number={4},
+  pages={797--826},
+  year={2000},
+  publisher={Elsevier}
+}
+
+@article{amor2009regularized,
+  title={Regularized formulation of the variational brittle fracture with unilateral contact: Numerical experiments},
+  author={Amor, Hanen and Marigo, Jean-Jacques and Maurini, Corrado},
+  journal={Journal of the Mechanics and Physics of Solids},
+  volume={57},
+  number={8},
+  pages={1209--1229},
+  year={2009},
+  publisher={Elsevier}
+}
+
+
 @Book{Ericson:2004:RCD:1121584,
   Title                    = {Real-Time Collision Detection (The Morgan Kaufmann Series in Interactive 3-D Technology)},
   Author                   = {Ericson, Christer},