H1426+428
[References]
Whipple: D. Horan et al., Astrophys. J. 571, 753 (2002); astro-ph/0202185
[correction]
D. Petry et
al., Astrophys.J. 580, 104-109 (2002)
D. Horan et
al., Proc. 28th ICRC (Tsukuba), p.2647 (2003)
HEGRA: F. Aharonian et al., Astron. Astrophys. 384, L23 (2002)
F. Aharonian et al., Astron. Astrophys.
403, 523 (2003)
CAT: A. Djannati-Atai et al., Astron. Astrophys. 391, L25-L28 (2002)
TACTIC: S. Thoudam, et al., Proc. 29th ICRC (Pune), Vol.4 p.363 (2005)
[Upper limit]
Yadav, K.K.
et al., arXiv:0905.3994 [Upper limit] <to appear in J. Phys. G.>
STACEE: Smith, D.A. et al., Astron. Astrophys. 459, 453-464 (2006) [Upper limit]
MAGIC: V.A. Acciari et al., arXiv:1911.06680 [astro-ph]