Robert Rettinger Xizhong Zheng Romain Gengler Burchard von Braunmühl Monotonically Computable Real Numbers. 459-479 2002 48 Math. Log. Q. 3 http://dx.doi.org/10.1002/1521-3870(200204)48:3<459::AID-MALQ459>3.0.CO;2-9 db/journals/mlq/mlq48.html#RettingerZGB02