TY  - RPRT
TI  - A systematic search for long-term variability in a large sample of X-ray sources
AU  - Maccacaro, Tommaso
AU  - Garilli, Bianca
AU  - Mereghetti, Sandro
PY  - 1987
UR  - https://ntrs.nasa.gov/citations/19870056867
ID  - 19870056867
ER  -