Финитная аппроксимируемость

Hsu, Tim; Wise, Daniel T. Ascending HNN extensions of polycyclic groups are residually finite.
    J. Pure Appl. Algebra 182, No.1, 65-78 (2003). [ISSN 0022-4049]

Rhemtulla, A.H.; Shirvani, M. The residual finiteness of ascending HNN-extensions of certain soluble groups.
    Ill. J. Math. 47, No.1-2, 477-484 (2003). [ISSN 0019-2082]

Raptis, E.; Varsos, D. The residual finiteness of HNN-extensions and generalized free products of nilpotent groups: A characterization.
    J. Aust. Math. Soc., Ser. A 53, No.3, 408-420 (1992).

Campbell, Robert I. Notes on the Baumslag-Solitar nonresidually finite examples.
    Proc. Am. Math. Soc. 109, No.1, 59-62 (1990).

Andreadakis, S.; Raptis, E.; Varsos, D. A characterization of residually finite HNN-extensions of finitely generated Abelian groups.
    Arch. Math. 50, No.6, 495-501 (1988).

Andreadakis, S.; Raptis, E.; Varsos, D. Residual finiteness and Hopficity of certain HNN extensions.
    Arch. Math. 47, 1-5 (1986).

Shirvani, M. On residually finite HNN-extensions.
    Arch. Math. 44, 110-115 (1985).

Baumslag, B.; Tretkoff, M. Residually finite HNN-extensions.
    Comm. Algebra. 6, 179-194 (1978).

Cohen, D.E. Residual finiteness and Britton's lemma.
    J. Lond. Math. Soc. 16, 232-234 (1977).

Хопфовость и конечные гомоморфные образы

Sapir, Mark; Wise, Daniel T. Ascending HNN extensions of residually finite groups can be non-Hopfian and can have very few finite quotients.
    J. Pure Appl. Algebra 166, No.1-2, 191-202 (2002). [ISSN 0022-4049]

Geoghegan, Ross; Mihalik, Michael L.; Sapir, Mark; Wise, Daniel T. Ascending HNN extensions of finitely generated free groups are Hopfian.
    Bull. Lond. Math. Soc. 33, No.3, 292-298 (2001). [ISSN 0024-6093]

Andreadakis, S.; Raptis, E.; Varsos, D. Hopficity of certain HNN-extensions.
    Comm. Algebra, v.20, No.5, 1511-1533 (1992).

Andreadakis, S.; Raptis, E.; Varsos, D. Residual finiteness and Hopficity of certain HNN extensions.
    Arch. Math. 47, 1-5 (1986).

[A] Meter, David. Non-hopfian groups.
    J. London Math. Soc. 26, No.2, 265–270 (1982).

Аппроксимируемость относительно сопряженности

Wong, P.C.; Tang, C.K. Conjugacy separability of certain HNN extensions of conjugacy-separable groups.
    Algebra Colloq. 7, No.2, 147-158 (2000). [ISSN 1005-3867; ISSN 0219-1733]

Kim, Goansu; Tang, C.Y. A criterion for the conjugacy separability of certain HNN extensions of groups.
    J. Algebra 222, No.2, 574-594, Art. No.jabr.1999.8034 (1999). [ISSN 0021-8693]

Raptis, E.; Talelli, O.; Varsos, D. On the conjugacy separability of certain graphs of groups.
    J. Algebra 199, No.1, 327-336, Art. No.JA977176 (1998). [ISSN 0021-8693]

[A]^* Wilson, J.S.; Zalesskii, P.A. Conjugacy separability of certain Bianchi groups and HNN extensions.
    Math. Proc. Camb. Philos. Soc. 123, No.2, 227-242 (1998). [ISSN 0305-0041]

[A]^* Wong, P.C.; Tang, C.K. Conjugacy separability of certain HNN extensions.
    Algebra Colloq. 5, No.1, 25-31 (1998). [ISSN 1005-3867]

[A] Kim, Goansu; Tang, C.Y. Conjugacy separability of HNN-extensions of abelian groups.
    Arch. Math. 67, No.5, 353-359 (1996). [ISSN 0003-889X]

Lochart, Jody Meyer. An HNN-extension with cyclic associated subgroups and with unsolvable conjugacy problem.
    Trans. Amer. Math. Soc. 313, No.1, 331–345 (1989).

[A] Dyer, Joan L. Separating conjugates in amalgamated free products and HNN-extensions.
    J. Austral. Math. Soc. A29, No.1, 35–51 (1980).

Отделимость конечно порожденных подгрупп

Metaftsis, V.; Raptis, E. Subgroup separability of HNN-extensions with Abelian base group.
    J. Algebra 245, No.1, 42-49 (2001). [ISSN 0021-8693]

[A]^* Wong, P.C. Subgroup separability of certain HNN extensions of finitely generated Abelian groups.
    Rocky Mt. J. Math. 27, No.1, 359-365 (1997). [ISSN 0035-7596]

[A] Wong, P.C. Strong residual finiteness of certain HNN-extensions.
    Bull. Malays. Math. Soc. 14, No.2, 69–72 (1991).

Shakhova, N.G. Finite approximability with respect to occurrence of some HNN-extensions.
    Mosc. Univ. Math. Bull. 36, No.5, 71-77 (1981).

Shakhova, N.G. On the finite approximability with respect to the occurrence of some HNN-extensions.
    Vestn. Mosk. Univ., Ser. I 1981, No.5, 57-62 (1981).

Отделимость циклических подгрупп

Kim, Goansu; Tang, C.Y. Cyclic subgroup separability of HNN-extensions with cyclic associated subgroups.
    Can. Math. Bull. 42, No.3, 335-343 (1999). [ISSN 0008-4395]

Wong, P.C.; Tang, C.K. Cyclic subgroup separability of certain HNN extensions of finitely generated Abelian groups.
    Rocky Mt. J. Math. 29, No.1, 347-356 (1999). [ISSN 0035-7596]

[A] Wong, Peng Choon; Gan, Hui Woan Cyclic subgroup separability of certain HNN extensions.
    Bull. Malays. Math. Soc., II. Ser. 22, No.2, 169-177 (1999). [ISSN 0126-6705]

Rosenberger, G.; Sasse, S.L. Residual properties of HNN-extensions with cyclic associated subgroups.
    Algebra Colloq. 3, No.1, 91-96 (1996). [ISSN 1005-3867]

Kim, Goansu Cyclic subgroup separability of HNN extensions.
    Bull. Korean Math. Soc. 30, No.2, 285-293 (1993).

Нильпотентная аппроксимируемость

Raptis, E.; Varsos, D. The residual nilpotence of HNN-extensions with base group a finite or a f.g. abelian group.
    J. Pure Appl. Algebra 76, No.2, 167-178 (1991).

Raptis, E.; Varsos, D. Residual properties of HNN-extensions with base group an Abelian group.
    J. Pure Appl. Algebra 59, No.3, 285-290 (1989).

[A] Raptis, E.; Varsos, D. Some residual properties of certain HNN extensions.
    Bull. Greek Math. Soc. 28, 81-87 (1987).

Мощные группы

[A] Wong, P.C.; Rostami-Ravari, A. Weak potency of HNN extensions.
    Proceedings of the 31st Iranian mathematics conference, Tehran, Islamic Republic of Iran, August 27-30, 2000. Appendix containing errata and additional papers. Tehran: University of Tehran, 21-24 (2000).

^* Имеется печатный оттиск данной статьи