Docs: Fix ARKODE_VERNER_8_5_6 reference (#546)

doc/arkode/guide/source/Butcher.rst

@@ -915,7 +915,7 @@ or :c:func:`ARKodeButcherTable_LoadERK`.
 Accessible via the string ``"ARKODE_VERNER_8_5_6"`` to
 :c:func:`ARKStepSetTableName`, :c:func:`ERKStepSetTableName` or
 :c:func:`ARKodeButcherTable_LoadERKByName`.
-This is the default 6th order explicit method (from :cite:p:`Ver:78`).
+This is the default 6th order explicit method (from :cite:p:`HEJ:76`).
 
 .. math::
 

doc/shared/sundials.bib

@@ -1880,6 +1880,14 @@ @article{Gust:94
   doi     = {10.1145/198429.198437}
 }
 
+@techreport{HEJ:76,
+  title = {User's guide for {DVERK}: {A} subroutine for solving non-stiff {ODE}'s},
+  author = {Hull, TE and Enright, WH and Jackson, KR},
+  year = {1976},
+  number = {100},
+  institution={University of Toronto. Department of Computer Science}
+}
+
 @article{Jay:21,
   title     = {Symplecticness conditions of some low order partitioned methods for non-autonomous Hamiltonian systems},
   author    = {Jay, Laurent O},
@@ -2133,17 +2141,6 @@ @article{Sof:04
   doi = {10.1016/j.mcm.2005.01.010}
 }
 
-@article{Ver:78,
-  author  = {Verner, J.H},
-  title   = {Explicit Runge-Kutta methods with estimates of the local truncation error},
-  journal = {SIAM Journal of Numerical Analysis},
-  volume  = {15},
-  number  = {4},
-  pages   = {772-790},
-  year    = {1978},
-  doi     = {10.1137/0715051}
-}
-
 @article{Ver:10,
   author  = {Verner, J.H},
   title   = {Numerically optimal {Runge–Kutta} pairs with interpolants},