TY  - RPRT
TI  - Upper limits from hard X-ray observations of five BL Lacertae objects
AU  - Bezler, M.
AU  - Gruber, D. E.
AU  - Rothschild, R. E.
PY  - 1988
UR  - https://ntrs.nasa.gov/citations/19890029313
ID  - 19890029313
ER  -