M. Ashiq and Q. Mushtaq, Finite presentation of a linear-fractional group,
Algebra Colloq. 12 (2005), no. 4, 585--589.
H.S.M. Coxeter, The abstract group
Gm;n;p,
Trans. Amer. Math. Soc. 45 (1939), no. 1, 73--150.
Q. Mushtaq, Modular group acting on real quadratic fields,
Bull. Aust. Math. Soc. 37 (1988), no. 2, 303--309.
Q. Mushtaq, On word structure of the modular group over finite and real quadratic fields,
Discrete Math. 178 (1998), no. 1-3, 155--164.
Q. Mushtaq and M. Aslam, Group generated by two elements of orders two and six acting on
R and
Q(
p,n),
Discrete Math. 179 (1998), no. 1-3, 145--154.
Q. Mushtaq and G.C.Rota, Alternating Groups as Quotients of two generator groups,
Adv. Math. 96 (1992), no. 1, 113--121.
W.W. Stothers, Subgroup of the (2,3,7)-triangle group,
Manuscripta Math. 20 (1977), no. 4, 323--334.