Baumslag G. On generalised free products[J]. Mathematische Zeitschrift, 1962, 78(1): 423-438.
2
Baumslag G. ON THE RESIDUAL FINITENESS OF GENERALISED FREE PRODUCTS OF NILPOTENT GROUPS[J]. Transactions of the American Mathematical Society, 1963, 106(2): 193-209.
3
Kharlampovich O, Myasnikov A. Hyperbolic groups and free constructions[J]. Transactions of the American Mathematical Society, 1996, 350(2): 571-613.
4
Lyndon R C. Groups with parametric exponents[J]. Transactions of the American Mathematical Society, 1960, 96(3): 518-533.
5
Baumslag G. Groups with the same lower central sequence as a relatively free group. I. The groups[J]. Transactions of the American Mathematical Society, 1967, 129(2): 308-321.
6
Baumslag G. Residual nilpotence and relations in free groups[J]. Journal of Algebra, 1965, 2(3): 271-282.
7
Gilbert Baumslag. Wreath products and extensions. 1963.
8
Baumslag G. Wreath products and finitely presented groups[J]. Mathematische Zeitschrift, 1961, 75(1): 22-28.
9
Kovcs L G. Groups with regular automorphisms of order four[J]. Mathematische Zeitschrift, 1961, 75(1): 277-294.
10
Andreas Baudisch. Subgroups of semifree groups. 2005.