@book {14717,
	title = {Balkan V{\"o}gel. Ein ornithologisches Tagebuch.},
	year = {1920},
	pages = { 210 pp.},
	address = {Altenburg.},
	keywords = {Aves},
	author = {Gengler, J.}
}
@book {12535,
	title = {Avifauna Macedonia.},
	year = {1920},
	pages = {270 pp.},
	address = {M{\"u}nchen},
	keywords = {Aves},
	author = {Stresemann, E.}
}
