@InCollection{Beckert98,
author = {Bernhard Beckert},
title = {Rigid {$E$}-Unification},
part = {2: Special Calculi and Refinements},
volume = {{I}: Foundations},
pages = {265--289},
booktitle = {Automated Deduction --- A Basis for Applications},
editor = {Wolfgang Bibel and Peter H. Schmitt},
publisher = {Kluwer, Dordrecht},
year = {1998}
}