I am pleased that Springer-Verlag has decided to reprint this book， giving
me the opportunity to include a number of corrections. The changes in this printing are mainly limited to the correction of typographical and other minor errors which I have become aware of since 1986. A couple of changes should be mentioned explicitly. The definition of completely srngular in Chapter H.2 has been modified slightly， the proof of Theorem I1.2.3 has been changed accordingly， and Appendix C has been rewritten. I would like to thank J. Bruna， K. Burke， J. Fleron， W. Rudin， W. Stoll and E. Straube for their helpful comments.
Soon after publication of the first edition， E. Martinelly brought to my at-tention some papers by F. Severi and G. Fichera， which play a fundamental role in the development of the so-called CR extension theorem. This result-a strengthening of the celebrated Hartogs Extension Theorem-involves the characterization of boundary values of holomorphic functions by the tangen- tial Cauchy-Riemann equations， i.e.， by intrinsic conditions on the boundary.Unfortunately， much of the literature written in English related to tbis topic had been unaware of the work of Severi and Fichera， and thus it presents an inaccurate account of its history. In view of the new evidence and of the great interest which the Hartogs and CR extension phenomena have generated over many decades， I have completely revised and expanded the relevant sections
of the Notes to Chapter IV. and I have added several new references to
the bibliography. It is my pleasure to thank R. Gunning， L. Hormander， J.J.Kohn， E. Martinelly， and H. Rossi for their assistance in setting the record straight.
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