Toshiyasu Arai Epsilon substitution method for <i>ID</i><sub>1</sub>(Pi<sub>1</sub><sup>0</sup> or Sigma<sub>1</sub><sup>0</sup>). 163-208 2003 121 Ann. Pure Appl. Logic 2-3 http://dx.doi.org/10.1016/S0168-0072(02)00112-4 db/journals/apal/apal121.html#Arai03