[CITATION][C] Bird Tracks and Sign of North America
M Elbroch, E Marks�- Mechanicsburg, PA: Stackpole Books, 2001
[CITATION][C] Bird tracks and sign: Mechanicsburg
M Elbroch, E Marks - 2001 - Stackpole Books
[CITATION][C] Bird trackSand Sign: Aguide to North American Species
M Elbroch, E MarkS, CD BoretOS - 2001 - Stackpole Books, PennSylvania�…