Fairouz Kamareddine Roel Bloo De Bruijn's syntax and reductional behaviour of lambda-terms: the untyped case. 109-131 2005 62 J. Log. Algebr. Program. 1 http://dx.doi.org/10.1016/j.jlap.2004.01.001 db/journals/jlp/jlp62.html#KamareddineB05