Merge pull request #97 from HEPLean/Tensors-V2

feat: Add general tensor definitions

docs/references.bib

@@ -20,6 +20,23 @@
   year          = "2022"
 }
 
+@Article{         Dreiner:2008tw,
+  author        = "Dreiner, Herbi K. and Haber, Howard E. and Martin, Stephen
+                  P.",
+  title         = "{Two-component spinor techniques and Feynman rules for
+                  quantum field theory and supersymmetry}",
+  eprint        = "0812.1594",
+  archiveprefix = "arXiv",
+  primaryclass  = "hep-ph",
+  reportnumber  = "BN-TH-2008-12, SCIPP-08-08, FERMILAB-PUB-09-855-T,
+                  BN-TH-2008-12 and SCIPP-08/08",
+  doi           = "10.1016/j.physrep.2010.05.002",
+  journal       = "Phys. Rept.",
+  volume        = "494",
+  pages         = "1--196",
+  year          = "2010"
+}
+
 @Article{         Lohitsiri:2019fuu,
   author        = "Lohitsiri, Nakarin and Tong, David",
   title         = "{Hypercharge Quantisation and Fermat's Last Theorem}",