# What are the normal subgroups of the finite Coxeter Groups of type Bn?

Let $$Bn=⟨ρ0,ρ1,…,ρn−1⟩B_n = \langle \rho_0,\rho_1,\ldots,\rho_{n-1} \rangle$$ subject to the relations that $$(ρiρj)mi,j=id(\rho_i\rho_j)^{m_{i,j}} = id$$ with $$mi,i=1m_{i,i} = 1$$, $$mi,j=2m_{i,j} = 2$$ for $$|i−j|≥2|i-j|\ge 2$$, $$mi,i+1=3m_{i,i+1} =3$$ for $$0≤i and finally $$mn−1,n=4m_{n-1,n} =4$$. What are the normal subgroups of $$BnB_n$$ and where might I find a reference? Computationally, I see that for all $$n>4n>4$$ there are 9 of them and I would like to find some source which describes them explicitly.