[Bagyura J, Szitta T, Haraszthy L, Firmánszky G, Viszló L, Kovács A, Demeter I & Horváth M2002: Population increase of eastern imperial eagle (Aquila heliaca) in Hungary between 1 980 and 2000. Aquila 1 07-1 08: 1 33-1 44.]Search in Google Scholar
[BirdLife International 201 3: Species factsheet: Aquila heliaca. Retrieved December 1 , 201 3, from http://www.birdlife.org.]Search in Google Scholar
[Danko Š 1 996: Beringungsergebnisse am Kaiseradler Aquila heliaca im Nordwesten des Brutareals, 389-403. In: Meyburg B-U & Chancellor Rd (eds), Eagle Studies. World Working Group on Birds of Prey (WWGBP), Berlin, London & Paris, 549.]Search in Google Scholar
[Demerdzhiev D 2011 : Iztochniyat tsarski orel (Aquila heliaca heliaca Savigny, 1 809) (Accipitridae - Aves) v Balgariya - razprostranenie, biologiya, ekologiya, chislenost i merki za opazvane [Eastern imperial eagle (Aquila heliaca heliaca Savigny, 1 809) (Accipitridae - Aves) in Bulgaria - distribution, biology, ecology, numbers, and conservation measures]. Synopsis of the PhD. thesis. BASNMNH, Sofia, 39. [In Bulgarian] ]Search in Google Scholar
[Demerdzhiev D, Horváth M, Kovács A, Stoychev S & Karyakin I 2011 .: Status and population trend of the eastern imperial eagle (Aquila heliaca) in Europe in the period 2000-201 0. Acta zoologica Bulgarica Supplementum 3: 5-1 4.]Search in Google Scholar
[Demerdzhiev D, Gradev G, Stoychev S, Ivanov I, Petrov T & Marin S 2011 b: Increase of the population of the eastern imperial eagle (Aquila heliaca) in Bulgaria. Acta zoologica Bulgarica Supplementum 3: 41-54.]Search in Google Scholar
[Galabov Z 1 982: Fiziogeografski rayoni [Physiographic regions], 11 5-21 5. In: Galabov Z (ed), Geografiya na Balgariya , tom 3. Fiziogeografiya [Geography of Bulgaria, vol. 3. Physiography]. BAS, Sofia, 31 5. [In Bulgarian] ]Search in Google Scholar
[Gradev G, Matarranz V, Dobreva E, Popov D, Marin S, Ivanov I & Zhelev P 2011 : First results of the tracking of eastern imperial eagles(Aquila heliaca) tagged with radio-transmitters in Bulgaria. Acta Zoologica Bulgarica Supplementum 3: 21-28.]Search in Google Scholar
[Gradev G, Zhelev P, Marin S 201 4: Identifying the home range of breeding pairs of eastern imperial eagles (Aquila heliaca) through radio-tracking in Bulgaria. Slovak Raptor Journa 8(1 ): 63.]Search in Google Scholar
[IUCN 201 3: IUCN Red list of threatened species. Version 201 3.2. Retrieved December 1 , 201 3 from www.iucnredlist.org.]Search in Google Scholar
[Katzner T, Bragin E & Milner-Gulland E 2006: Modeling populations of long-lived birds of prey for conservation: a study of imperial eagles (Aquila heliaca) in Kazakhstan. Biological Conservation 1 32: 322-335. DOI: http://dx.doi.org/10.1016/j.biocon.-2006.04.024.]Search in Google Scholar
[Kenward R 2001 : A manual for wildlife radio tagging. 2nd edition. Academic Press, New York, 350.]Search in Google Scholar
[Ortega E, Manosa S, Margalida A, Sanchez R, Oria J & Gonzalez L 2009: A demographic description of the recovery of the vulnerable Spanish imperial eagle Aquila adalberti. Oryx 43: 11 3-1 21 . DOI: http://dx.doi.org/10.1017/S0030605307991048.10.1017/S0030605307991048]Search in Google Scholar
[Meyburg B-U, Haraszthy L, Meyburg C & Viszlo L 1 995: Satelliten und Bodentelemetrie A. heliaca binemjungen Kaiseradler Aquila heliaca: Familien auflösung und Dispersion. Vogelwelt 11 6: 1 53-1 57.]Search in Google Scholar
[Petrov T & Stoychev S 2002: Natsionalen plan za deystvie za tsarskiya orel (A. heliaca) v Balgariya [National Action Plan for the imperial eagle (A. heliaca)], 1 32-1 61 . In: Iankov P (ed), Global threatened birds in Bulgaria. National Action plans for the conservation. Part 1 . BSPB-MOSV, Conservation Series, Book 4, BSPB, Sofia, 227. [In Bulgarian] ]Search in Google Scholar
[Stoychev S, Ivanov I, Petrov T, Marin S, Demerdzhiev D, Gradev G & Domuschiev D 2004: Status of the eastern imperial eagle (Aquila heliaca) in Bulgaria between 1 994 and 2002, 653-660. In: Chancellor RD & Meyburg B-U (eds): Raptors worldwide. Proceedings of the VI world conference on birds of prey and owls. Budapest, Hungary 1 8-23 May 2003World Working Group on Birds of Prey and Owls & MME/BirdLife Hungary, Berlin & Budapest, 867.]Search in Google Scholar
[Stoychev S, Demerdzhiev D & Petrov T 201 3: Plan za deystvie za opazvane na krastatiya orel (A. heliaca) v Balgariya 201 3-2022 [National Action plan for the conservation of the eastern imperial eagle (A. heliaca) in Bulgaria 201 3-2022]. Ministry of Environment andWater, Sofia, 76. [In Bulgarian] ]Search in Google Scholar
[Voos KH 1 960: Atlas of European birds. Nelson, Edinburgh, 284. ]Search in Google Scholar
