How tall is the automorphism tower of a group?

• J. D. Hamkins, “How tall is the automorphism tower of a group?,” in Logic and algebra, Y. Zhang, Ed., Providence, RI: Amer.~Math.~Soc., 2002, vol. 302, pp. 49-57.
@INCOLLECTION{Hamkins2001:HowTall?,
AUTHOR = {Hamkins, Joel David},
TITLE = {How tall is the automorphism tower of a group?},
BOOKTITLE = {Logic and algebra},
SERIES = {Contemp.~Math.},
VOLUME = {302},
PAGES = {49--57},
PUBLISHER = {Amer.~Math.~Soc.},
}