Add reference

Author: njericha

README.md

@@ -5,3 +5,20 @@ See documentation here: https://mpf-optimization-laboratory.github.io/MatrixTens
 Factorize a 3rd order tensor Y into a matrix A and 3rd order tensor B: Y=AB. Componentwise, this is:
 
 Y[i,j,k] = sum_{r=1}^R ( A[i,r] * B[r,j,k] )
+
+# Reference
+If you find this package at all helpful, please cite the associated paper which is avalible for preprint here:
+https://friedlander.io/publications/2024-sediment-source-analysis/
+
+```
+@misc{graham_tracing_2024,
+	title = {Tracing {Sedimentary} {Origins} in {Multivariate} {Geochronology} via {Constrained} {Tensor} {Factorization}},
+	url = {https://friedlander.io/publications/2024-sediment-source-analysis/},
+	urldate = {2024-06-28},
+	author = {Graham, Naomi and Richardson, Nicholas and Friedlander, Michael P. and Saylor, Joel},
+	month = may,
+	year = {2024},
+  note = {Preprint},
+  journal = {Preprint},
+}
+```