The Cornell University Library Historical Math Monographs collection comprises selected monographs with expired copyrights chosen from the mathematics field. The majority of these monographs were physically brittle, decaying, and in need of rescue. They were digitally scanned, and facsimile editions were created on acid-free paper.
Chapter X: Differential equations in more than two variables
Wilson, Edwin Bidwell, Massachusetts Institute of Technology, et al. (1912)