Papers on the hierarchical model

H. Koch, P. Wittwer: A non--Gaussian renormalization group fixed point for
hierarchical scalar lattice field theories
Commun. Math. Phys., 106(1986), 495--532.
https://projecteuclid.org/euclid.cmp/1104115787

H. Koch, P. Wittwer: On the renormalization group transformation
for scalar hierarchical models
Commun. Math. Phys., 138(1991), 537--568.
https://projecteuclid.org/euclid.cmp/1104203042

H. Koch, P. Wittwer: A nontrivial renormalization group fixed point
for the Dyson--Baker hierarchical model
Commun. Math. Phys., 164(1994), 627--647.
https://projecteuclid.org/euclid.cmp/1104270951

H. Koch, P. Wittwer: Bounds on the zeros
of a nontrivial renormalization group fixed point
Math. Phys. EJ, 1(1995) 24pp.
https://web.ma.utexas.edu/mpej/Vol/1/6.ps