Published in Journal für Ornithologie, in 1921, in volume 69, pages 239-258

Published in Journal für Ornithologie, in 1921, in volume 69, pages 573-575

Published in Journal für Ornithologie, in 1921, in volume 69, pages 572-573

Published in Journal für Ornithologie, in 1921, in volume 69, pages 570-572

Published in Journal für Ornithologie, in 1921, in volume 69, pages 535-570

Published in Journal für Ornithologie, in 1921, in volume 69, pages 527-535

Published in Journal für Ornithologie, in 1921, in volume 69, pages 505-512

Published in Journal für Ornithologie, in 1921, in volume 69, pages 469-504

Published in Journal für Ornithologie, in 1921, in volume 69, pages 466-468

Published in Journal für Ornithologie, in 1921, in volume 69, pages 465-466

Published in Journal für Ornithologie, in 1921, in volume 69, pages 464-465

Published in Journal für Ornithologie, in 1921, in volume 69, pages 461-464

Published in Journal für Ornithologie, in 1921, in volume 69, pages 457-461

Published in Journal für Ornithologie, in 1921, in volume 69, pages 426-456

Published in Journal für Ornithologie, in 1921, in volume 69, pages 408-426

Published in Journal für Ornithologie, in 1921, in volume 69, pages 406-408

Published in Journal für Ornithologie, in 1921, in volume 69, pages 400-406

Published in Journal für Ornithologie, in 1921, in volume 69, pages 269-399

Published in Journal für Ornithologie, in 1921, in volume 69, pages 266-268

Published in Journal für Ornithologie, in 1921, in volume 69, pages 259-266

Published in Journal für Ornithologie, in 1921, in volume 69, pages 258-259

Published in Journal für Ornithologie, in 1921, in volume 69, pages 218-239

Published in Journal für Ornithologie, in 1921, in volume 69, pages 201-211

Published in Journal für Ornithologie, in 1921, in volume 69, pages 172-200

Published in Journal für Ornithologie, in 1921, in volume 69, pages 153-172

Published in Journal für Ornithologie, in 1921, in volume 69, pages 139-147

Published in Journal für Ornithologie, in 1921, in volume 69, pages 119-120

Published in Journal für Ornithologie, in 1921, in volume 69, pages 118

Published in Journal für Ornithologie, in 1921, in volume 69, pages 115-117

Published in Journal für Ornithologie, in 1921, in volume 69, pages 112-115

Published in Journal für Ornithologie, in 1921, in volume 69, pages 91-111

Published in Journal für Ornithologie, in 1921, in volume 69, pages 90-91

Published in Journal für Ornithologie, in 1921, in volume 69, pages 50-90

Published in Journal für Ornithologie, in 1921, in volume 69, pages 46-49

Published in Journal für Ornithologie, in 1921, in volume 69, pages 45-46

Published in Journal für Ornithologie, in 1921, in volume 69, pages 41-45

Published in Journal für Ornithologie, in 1921, in volume 69, pages 13-38

Published in Journal für Ornithologie, in 1921, in volume 69, pages 1-13