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@@ -6,3 +6,13 @@ U.S. Geological Survey (USGS) hazard software [*nshmp-haz*][1]. This model was l
 
 For details on the format of this model, see the *nshmp-haz*
 [user guide and implementation reference][2].
+
+## Reference
+
+Petersen, M.D, Shumway, A.M., Powers, P.M., Mueller, C.S., Moschetti, M.P., Frankel, A.D.,
+Rezaeian, S., McNamara, D.E., Luco, N., Boyd, O.S., Rukstales, K.S., Jaiswal, K.S., Thompson, E.M.,
+Hoover, S.M., Clayton, B.S., Field, E.H., and Zeng, Y., 2020, The 2018 update of the U.S. National
+Seismic Hazard Model: Overview of model and implications, _Earthquake Spectra_, 36(1) p. 5–41.
+
+[1]: https://code.usgs.gov/ghsc/nshmp/nshmp-haz
+[2]: https://code.usgs.gov/ghsc/nshmp/nshmp-haz/-/blob/main/docs/README.md