Avibase - Extensive database information system about all birds of the world.
BirdLife - BirdLife International is the world’s largest nature conservation partnership. Together we are 120 BirdLife Partners worldwide – one per country or territory – and growing.
Europa.eu - The Directorate-General for Environment is the European Commission department responsible for EU policy on the environment.
AERC - Association of European Records and Rarities Committees.
uBio - Initiative within the science library community to join international efforts to create and utilize a comprehensive and collaborative catalog of known names of all living (and once-living) organisms.
ITIS - Integrated Taxonomic Information System.
ZOOtierliste - Database for the current and former vertebrate inventories of European zoos and other public collections.
WZD - Online database of the world's zoological gardens and similar establishments.
ZOOchat - World's largest community built especially for zoo and animal conservation enthusiasts.
GlobalSpecies - Institutions and Zoos.
AOPK ČR - Agency for Nature and Landscape Conservation of the Czech Republic.
FKCSO - Faunistic Commission of the Czech Society for Ornithology (ČSO).
BioLib - Biological Library. International encyclopedia of plants, fungi and animals.
ČSO - Czech Society for Ornithology is a voluntary interest association of professionals and amateurs engaged in research and protection of birds, people interested in birdwatching and nature lovers.
SOPSR - State Nature Conservancy of the Slovak Republic is a specific professional organization of the Ministry of Environment of the Slovak Republic with nationwide coverage, in particular in ensuring tasks in the field of nature protection including management of caves
SOS - Slovak Ornithological Society - BirdLife Slovakia. It is a non- governmental organization, civic association, which the main role is to protect and research the nature, especially the wild birds and its habitats.
BOU - Founded in 1858, the BOU is one of the world's oldest and most respected ornithological organisations with an international membership stretching across all continents.
Other sources are provided on the respective pages.