van Kampen, E. R. Invariants derived from looping coefficients. (English) Zbl 0019.23601 Am. J. Math. 60, 595-610 (1938). Page: −5 −4 −3 −2 −1 ±0 +1 +2 +3 +4 +5 Show Scanned Page Cited in 1 ReviewCited in 2 Documents Keywords:Topology PDFBibTeX XMLCite \textit{E. R. van Kampen}, Am. J. Math. 60, 595--610 (1938; Zbl 0019.23601) Full Text: DOI