Two of the following papers were published in a journal that is hard to find in libraries. If you can't find something here, write me and I'll try to find the file.

• Dehn functions and L_1-norms of finite presentions, .pdf, appeared in "Algorithms and Classification in Combinatorial Group Theory", edited by G. Baumslag and C. F. Miller III, Springer-Verlag, MSRI series vol. 23, 1991. In this paper I applied techniques of algebraic topology to compute lower bounds for Dehn functions (Gromov calls one of these techniques "Gersten's lemma", which is used but not stated explicitly in this paper), and I produced an example of a 1-relator group whose Dehn function, as I prove here, grows faster than any iterated exponential. The figures (done in an obsolete version of MacDraw) are not available in this file.
• (with H. Short) Rational subgroups of biautomatic groups, .pdf, appeared in Annals of Mathematics, vol. 134 (1991) 125--158.
• Bounded cocycles and combings of groups, .dvi, .ps, .pdf, .tex appeared in International Journal of Algebra and Computation 2 (1992) 307-326 (with an appendix by Domingo Toledo). The main technical result of this paper (Theorem 3.1) is that a central infinite cyclic extension of a finitely generated group G defined by a bounded cocycle is quasi-isometric to the product Z x G. The result has two important applications, to the coincidence of two of the 8 geometries of 3-manifolds up to quasi-isometry and to the existence of a combable group which is not residually finite, both of which were first proved in this paper.
• The double exponential theorem for isodiametric and isoperimetric functions .ps, .pdf, .dvi, appeared in International Journal of Algebra and Computation 1(1991) 321-327. This paper contains a topological proof, based on the notion of folding due to Stallings, of the theorem first proved by D. E. Cohen, by a complexity analysis of the Nielsen reduction algorithm, that for every finitely presented group there is an isoperimetric function which is a double exponential in its minimal isodiametric function.
• Isoperimetric and isodiametric functions of finite presentations .ps, .pdf, .dvi, appeared in Geometric Group Theory, Volume 1, edited by G. Niblo and M Roller, London Math. Society Lecture Notes Series 181 (1993) 79-96, Cambridge Univ. Press. The Dehn function and isodiametric functions of finite presentations are introduced. The word problem is solvable iff the Dehn function is recursive.
• Finiteness properties of asynchronously automatic groups .dvi, appeared in ``Geometric Group Theory", Proceedings of a Special Research Quarter at The Ohio state University, Spring 1992, edited by Ruth Charney, Michael Davis, and Michael Shapiro, pp. 121--134, Ohio State Univ. Mathematical Research Institute Publ. vol. 3, de Gruyter 1995. Several results related to asynchronous combings are proved in this paper. The two most significant, I now believe, are (1) all asynchronously combable groups have linearly bounded filling length, and (2) asynchronously automatic groups are of type F_3. The first is of interest since all compact 3-manifold groups satisfying Thurston's geometrization conjecture are asynchronously combable. (The property of linearly bounded filling length is called LCNH_1 in this paper; it was written a decade before Riley and I worked out the general theory of filling length of finitely presented groups.)
• Preservation and distortion of area in finitely presented groups .ps, .pdf, .dvi, appeared in GAFA, 6 (1996) 301--345.
• Cohomological lower bounds for isoperimetric functions on groups .ps, .pdf, .dvi appeared in Topology, 37 no. 5 (1998) pp. 1031-1072 (the publisher requires that, in order to the preprint version on my homepage, I cannot make any changes from the final published version.) The converse for the combination theorem for hyperbolic groups appears here.
• Banff lectures on hyperbolic and automatic groups .ps, .pdf, .dvi, appeared in the Proceedings of the CRM Summer School in Combinatorial Group Theory, Banff 1996, editor O. Kharlampovich, published by the AMS in the CRM Proceedings and Lecture Notes Series, vol. 17 (1999) (the web version incorporates corrections). This is the written version of two introductory lectures I gave at Banff. Some proofs are given while many are referred to the literature. There is a complete discussion of small cancellation conditions and hyperbolicity based on metric weight tests which is due to me and for which there is no other source in the literature.
• A cohomological characterization of hyperbolic groups .pdf(Dec. 1996).
I never published this paper and it seems that I forgot about it. I. Mineyev didn't, however, and he told me (2004) that he wanted to refer to a result in it, so I'm listing it here.
• (with D. Allcock) A homological character ization of hyperbolic groups .ps, .pdf, .dvi, appeared in Inventiones Math. 135 (1999) (3) 723-742. This contains an approximation theorem of independent interest, that every ell-one ($\ell_1$-) real-valued cycle on an arbitrary graph can be approximated by cycles of compact support.
• Distortion and L₁-homology .ps, .pdf, .dvi, appeared in Groups Korea 98, editors Baik, Johnson, and Kim, pages 133-164, published by de Gruyter, 2000.