1. Possible precursory tilts preceding some earthquakes (3.0 < M < 3.8) occurred in central Italy between February 1981 and June 1983;Bella;Earthquake Predict. Res.,1986
2. Possible propagation of tilt and strain anomalies: velocity and other characteristics;Bella;Earthquake Predict. Res.,1986
3. Tilt measurements and seismicity in central Italy over a period of approximately 3 years;Bella;Tectonophysics,1987
4. Very slow-moving crustal strain disturbances;Bella;Tectonophysics,1990
5. Ground tilt anomalies accompanying the main earthquakes occurred in the central Apennines (Italy) during the period 1986–1989;Bella;Nuovo Cimento,1993