1. Benson, C., Jenkins, J., Lipsman, R.L., Ratcliff, G.: A geometric criterion for Gelfand pairs associated with the Heisenberg group. Pac. J. Math. 178(1), 1–36 (1997)
2. Benson, C., Ratcliff, G.: A classification of multiplicity free actions. J. Algebra 181(1), 152–186 (1996)
3. Benson, C., Ratcliff, G.: The space of bounded spherical functions on the free 2-step nilpotent Lie group. Transform. Groups 13(2), 243–281 (2008)
4. Benson, C., Ratcliff, G.: Maple 15 worksheets for actions
$$Sp(6)\times U(3):M_{6,3}({\mathbb{C}})$$
S
p
(
6
)
×
U
(
3
)
:
M
6
,
3
(
C
)
and
$$Sp(4)\times U(4):M_{4,4}({\mathbb{C}})$$
S
p
(
4
)
×
U
(
4
)
:
M
4
,
4
(
C
)
.
http://core.ecu.edu/math/bensonf/research/research.html
(2012)
5. Benson, C., Ratcliff, G.: Geometric models for the spectra of certain Gelfand pairs associated with Heisenberg groups. Ann. Mat. Pura Appl. (4), 192(4), 719–740 (2013) (with Erratum on pages 741–743)