positive.bbl
\hyphenation{Post-Script Sprin-ger}
\begin{thebibliography}{10}

\bibitem{Burns}
R.~G. Burns.
\newblock On the intersection of finitely generated subgroups of a free group.
\newblock {\em Mathe. Z.}, 119:121--130, 1971.

\bibitem{Dicks}
W.~Dicks.
\newblock Equivalence of the strengthened {Hanna} {Neumann} conjecture and the
  amalgamated graph conjecture.
\newblock {\em Invent. Math.}, 117:373--389, 1994.

\bibitem{Gersten}
S.~M. Gersten.
\newblock Intersections of finitely generated subgroups of free groups and
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\newblock {\em Invent. Math.}, 71:567--591, 1983.

\bibitem{Howson}
A.~G. Howson.
\newblock On the intersection of finitely generated free groups.
\newblock {\em J. London Math. Soc.}, 29:428--434, 1954.

\bibitem{Imrich}
W.~Imrich.
\newblock On finitely generated subgroups of free groups.
\newblock {\em Arch. Math.}, 28:21--24, 1977.

\bibitem{Imrich2}
W.~Imrich.
\newblock Subgroup theorems and graphs.
\newblock {\em Combinatorial Mathematics V}, Lecture notes in mathematics, vol.
  622:1--27, Melbourne, 1983.

\bibitem{HNeumann}
H.~Neumann.
\newblock On intersections of finitely generated subgroups of free groups.
\newblock {\em Publ. Math., Debrecen}, 5:186--189, 1956.

\bibitem{WNeumann}
W.~Neumann.
\newblock On the intersection of finitely generated free groups.
\newblock In {\em Canberra 1989 (Lecture notes in Math., vol. 1456, pp
  161-170)}. Springer-Verlag, 1990.

\bibitem{Nickolas}
P.~Nickolas.
\newblock Intersections of finitely generated free groups.
\newblock {\em Bull. of the Australian Math. Soc.}, 34:339--348, 1985.

\bibitem{Servatius}
B.~Servatius.
\newblock A short proof of a theorem of {Burns'}.
\newblock {\em Mathe. Z.}, 184:133--137, 1983.

\bibitem{Stallings}
J.~R. Stallings.
\newblock Topology of finite graphs.
\newblock {\em Invent. Math.}, 71:551--565, 1983.

\bibitem{Tardos92}
G.~Tardos.
\newblock On the intersection of subgroups of a free group.
\newblock {\em Invent. Math.}, 108:29--36, 1992.

\bibitem{Tardos96}
G.~Tardos.
\newblock Toward the {Hanna} {Neumann} {Conjecture} using {Dicks'} method.
\newblock {\em Invent. Math.}, 123:95--104, 1996.

\bibitem{Whitney}
H.~Whitney.
\newblock Congruent graphs and the connectivity of graphs.
\newblock {\em Amer. J. Math.}, 54:150--168, 1932.

\end{thebibliography}
