1. F. Broecker, W. Ruppel, M. Wuensch, D. Agar, H. Daudel, U. Gaertner, O. Koechel, B. Morsbach, Process for selective catalytic reduction of exhaust gases from Diesel engines, European Patent specification EP 0515857, 1992.
2. H. Daudel, K.H. Marquardt, U. Gaertner, Exhaust gas aftertreatment device for internal combustion engines, US Patent specification US 5,369,956, 1994.
3. H. Schmelz, Method and apparatus for controlled introduction of a reducing agent into a nitrogen oxide-containing exhaust gas, US Patent specification US 5,628,186, 1997.
4. Selective NH3 gas sensor based on Langmuir–Blodgett polypyrrole film;Penza;Sens. Actuators B,1997
5. Application of conducting polyaniline as sensor material for ammonia;Dhawan;Sens. Actuators B,1997