1. JÄGER, P. Parametric Design of Post-tensioned Concrete Digesters. FIP Congress on Prestressed Concrete, Hamburg, 1990.
2. JÄGER, P. First Egg Shaped Sludge Digesters Using Exclusively Unbonded Tendons. FIP Symposium, Kyoto, Japan, 1993.
3. EVANS, E.; JÄGER, P.; SUTTER, G. Developments in the Design and Construction of Prestressed Concrete Digesters. FIP Symposium, Johannesburg, 1997.