Hard to find academic paper PDFs

This page contains scanned PDFs of hard-to-find academic papers. They are ugly and large, but no OCR has been performed, so the math is not horribly munged.

The papers

W.E. Donath and A.J. Hoffman. Lower bounds for partitioning of graphs. IBM J. Res. Develop., 17:420-425, 1973 (PDF)

M. Fiedler. Algebraic connectivity of graphs. Czech. Math. J., 23:298-305, 1973 (PDF)

M. Fiedler. A property of eigenvectors of non-negative symmetric matrices and its application to graph theory. Czech. Math. J., 25:619-633, 1975 (PDF)