Paper 1 for PRES'99:
Author(s): I.J. Halvorsen and S. Skogestad,
Title: Use of Shortcut Methods to Analyse Optimal Operation of Petlyuk
Distillation Columns
( Pres99-ShortCut..)

Paper 2 for PRES'99:
Author(s): I.J. Halvorsen, M. Serra, and S. Skogestad
Title: Evaluation of Self-Optimizing Control Structures for an
Integrated Petlyuk Distillation Column
(  Pres99-SelfOpt...)