Celebratio Mathematica

I. M. Sing­er and J. A. Thorpe: Lec­ture notes on ele­ment­ary to­po­logy and geo­metry. Scott, Fores­man and Co. (Glen­view, IL), 1967. Re­prin­ted in 1976. MR 213982 Zbl 0163.​44302 book

I. M. Sing­er and J. A. Thorpe: “The curvature of 4-di­men­sion­al Ein­stein spaces,” pp. 355–​365 in Glob­al ana­lys­is: Pa­pers in hon­or of K. Kodaira. Edi­ted by D. C. Spen­cer and S. Iy­anaga. Prin­ceton Uni­versity Press, 1969. MR 256303 Zbl 0199.​25401 incollection

I. M. Sing­er and J. A. Thorpe: Lec­ture notes on ele­ment­ary to­po­logy and geo­metry, re­print edition. Un­der­gradu­ate Texts in Math­em­at­ics. Spring­er (New York), 1976. Re­print of 1967 ori­gin­al. MR 413152 Zbl 0342.​54002 book