TY  - RPRT
TI  - Variable soft X-ray excesses in active galactic nuclei from nonthermal electron-positron pair cascades
AU  - Zdziarski, Andrzej A.
AU  - Coppi, Paolo S.
PY  - 1991
UR  - https://ntrs.nasa.gov/citations/19910062386
ID  - 19910062386
ER  -