Physics_EnergyLoss.md

@@ -14,7 +14,7 @@ and electronic tables from at http://pdg.lbl.gov/2018/AtomicNuclearProperties/in
 
 Barkas paper for original shell correction: https://www.nap.edu/read/20066/chapter/8 outdated, but simple to implement. 
 
-Shell correction are discussed by Bichsel 1992 in a more modern approach: 
+Shell correction are discussed by Bichsel 1992 in a more modern approach for heavy Z>56 targets: 
 [PhysRevA.46.5761.pdf](uploads/dcdaf0c5f26e0a6df81770028faa36af/PhysRevA.46.5761.pdf)