@article{PerpetualReduction,
author = {Femke van Raamsdonk and Paula Severi and Morten H. Sorensen and Hongwei Xi},		  
title = {Perpetual Reductions in lambda-calculus},
journal = {Information and Computation},
volume = 149,
number = 2,
pages = "173--225",
year = 1999,
month = "March"
}