Mrk 421

[References]

Whipple: Punch, M. et al., Nature 358,477 (1992)
           Schubnell, M.S. et al., ApJ 460, 644 (1996)
           Zweerink, J.A. et al., ApJ 490, L141 (1997)
           Krennrich, F. et al., ApJ 511, 149-156 (1999)
           Krennrich, F. et al., ApJ 575, L9-L13 (2002)
           Blazejowski, M. et al., ApJ 630, 130-141 (2005)
           Konopelko, A. et al., Proc. 30th ICRC (2007) / arXiv:0708.3857 [astro-ph]
           Daniel, M.K. et al., Gamma 2008 /arXiv:0810.0387
           D. Horan et al., Ap.J 695, 596-618 (2009)
           A. Pichel et al., ICRC2009 / arXiv:0908.0010

HEGRA: Petry, D. et al., A&A 311,  L13-L16 (1996)
            Aharonian, F.A. et al., A&A 350, 757-764 (1999)
            Aharonian, F. et al., ApJ 546, 8980902 (2001)
            Aharonian, F. et al., A&A 393, 89-99 (2002)

Whipple and HEGRA: Fosatti, G. et al., ApJ 677, 906-925 (2008)

CAT: Piron, F. et al., A&A 374, 895-906 (2001)

CANGAROO-II: Okumura, K. et al., ApJ 579, L9-L12 (2002)

STACEE: Boone, L.M. et al., ApJ 579, L5-L8 (2002)

Tibet AS-gamma: Amenomori, M. et al., ApJ 598, 242-249 (2003)

Milagro: Atkins, R. et al., Astrophys. J. 608, 680 (2004)
           A.A. Abdo et al., arXiv:1401.2161 [astro-ph]
           B. Patricelli et al., arXiv:1401.3336 [astro-ph]
           B. Patricelli et al., ICRC2013 / arXiv:1401.3348 [astro-ph]

H.E.S.S.: Aharonian, F. et al., Astron.Astrophys. 95 (2005) 437

MAGIC: J. Albert et al., ApJ 663, 125-138 (2007)
           F. Goebel et al., 30th ICRC (2007) / arXiv:0709.2032 [astro-ph]
           I. Donnarumma et al., Astrophys. J. 691, L13 (2009)
           G. Bonnoli et al, ICRC2009 / arXiv:0907.0831 [astro-ph]
           J. Aleksic et al., Astron. Astrophys. 519, A32 (2010)
           J. Aleksic et al., arXiv:1106.1589 [astro-ph]
           R. Wagner et al., ICRC 2011 / arXiv:1109.6774 [astro-ph]
           M.L. Ahnen et al., arXiv:1605.09017 [astro-ph]

VERITAS: S.J. Fegan et al., 30th ICRC (2007) / arXiv:0709.3659 [astro-ph]
           V.A. Acciari et al., arXiv:1106.1210 [astro-ph]
           N. Galante et al., ICRC 2011 / arXiv:1109.6059 [astro-ph]
           V.A. Acciari eet al., arXiv:1310.8150 [astro-ph]

VERITAS/MAGIC: V.A. Acciari et al., ApJ 703, 169-178 (2009)
           A.U. Abeysekara et al., arXiv:1611.04626 [astro-ph]

MAGIC/VERITAS et al.: J. Aleksic et al., arXiv:1502.02650 [astro-ph]
           A.U. Abeysekara et al., arXiv:2002.03567 [astro-ph](2010 flare)

Agile, Gasp-Webt, MAGIC, VERITAS: I. Donnaurumma et al., ApJ 691, L13 (2009)

Fermi-LAT/MAGIC/VERITAS: U. Barres de Almeida et al., ICRC 2011 / arXiv:1109.5887
           J. Aleksic et al., arXiv:1412.3576

HAGAR: A. Shukla et al., Fermi 2011 / arXiv:1110.6795
            A. Shukla et al.,  arXiv:1204.3850 [astro-ph]

TACTIC: P. Chandra et al., arXiv:1202.2984 [astro-ph]
            K.K. Singh et al., arXiv:1407.2359 [astro-ph]

ARGO-YBJ: B. Bartoli et al., ApJ Suppl. 222, 6 (2016) / arXiv:1511.06851 [astro-ph]

HAWC: A.U. Abeysekara et al., arXiv:1703.06968 [astro-ph]