G H Bagherzadeh,
Commutativity in one-relator groups, J. London Math.
Soc. (2) 13 (1976) 459–471 MR0407158
2
S D
Brodskiĭ, Equations over groups, and groups with
one defining relation, Sibirsk. Mat. Zh. 25 (1984)
84–103 MR741011
3
D J Collins,
Intersections of Magnus subgroups of one-relator groups,
from: "Groups: topological, combinatorial and arithmetic
aspects", London Math. Soc. Lecture Note Ser. 311, Cambridge
Univ. Press (2004) 255–296 MR2073350