Sy-David Friedman Michael Rathjen Andreas Weiermann 382-393 2013 164 Ann. Pure Appl. Log. 3 https://doi.org/10.1016/j.apal.2012.11.009 https://www.wikidata.org/entity/Q60500825 db/journals/apal/apal164.html#FriedmanRW13