Please cite this data as follows, and pay attention to the rights documented in the rights.txt:
Please respect the rights declared for each dataset in the download: 
2013. EOD - eBird Observation Dataset. doi:10.15468/aomfnb
Natural History Museum, University of Oslo: BioFokus doi:10.15468/jxbhqx
naturgucker.de: naturgucker doi:10.15468/uc1apo
Jagiellonian University, Institute of Environmental Sciences: The atlas of breeding birds in Małopolska doi:10.15468/h2rcid
Biologiezentrum Linz Oberoesterreich: Biologiezentrum Linz doi:10.15468/ynjblx
Institute of Nature Conservation, Polish Academy of Sciences: National System of Protected Areas in Poland - Animals doi:10.15468/she3lx
iNaturalist.org: iNaturalist research-grade observations doi:10.15468/ab3s5x
University of Washington Burke Museum Ornithology Collection, UWBM doi:10.15468/a2cmfl
The Norwegian Biodiversity Information Centre (NBIC): Norwegian Species Observation Service doi:10.15468/zjbzel
SPN - Service du Patrimoine naturel, Muséum national d'Histoire naturelle, Paris: Données ONF Faune-Flore-FOnge doi:10.15468/twp4c2
Kohli L. Bird Observational Records. Biodiversitäts-Monitoring Schweiz doi:10.15468/waz4ep
Natural History Museum, University of Tartu: Zoological collections of the University of Tartu
Natural History Museum, University of Oslo: Norwegian Biodiversity Information Centre - Other datasets doi:10.15468/tm56sc
National Museum of Natural History, Smithsonian Institution: NMNH occurrence DwC-A doi:10.15468/dipjcr
Royal Ontario Museum: Ornithology Collection Non Passeriformes - Royal Ontario Museum doi:10.15468/s0pqqg
Natural History Museum, University of Oslo: Bird skin collection, Natural History Museum, University of Oslo doi:10.15468/ex7wmt
Museum of Biological Diversity, The Ohio State University: Ohio State University Tetrapod Division - Bird Collection (OSUM) doi:10.15468/h6n5vl
SPN - Service du Patrimoine naturel, Muséum national d'Histoire naturelle, Paris: Inventaire National du Patrimoine Naturel : Oiseaux hivernants de France doi:10.15468/u7egmv
Estonian Nature Observations Database, Estonian Nature Observations Database doi:10.15468/dlblir
Institute of Nature Conservation, Polish Academy of Sciences: Birds of Cisna Community (southern Poland) doi:10.15468/xuxazg
GBIF-Sweden: Bird Ringing Centre in Sweden (NRM) doi:10.15468/cghs8p
GBIF-Sweden: Wetland Inventory (NV) doi:10.15468/yomo68
Institute of Nature Conservation, Polish Academy of Sciences: Carpatica Operation doi:10.15468/apgatj
SPN - Service du Patrimoine naturel, Muséum national d'Histoire naturelle, Paris: Inventaire National du Patrimoine Naturel : Oiseaux nicheurs de France doi:10.15468/wi1lpm
UMMZ Bird Collection doi:10.15468/lns1qm
Natural History Museum, University of Oslo: Bird tissue collection, Natural History Museum, University of Oslo doi:10.15468/cwhovx
Birdlife Finland: Tiira information service doi:10.15468/p09mpw