Algebraic Topology: Homotopy and Homology
《Algebraic Topology: Homotopy and Homology》 · 第 207 页 · Section 11
For vector bundles \(\xi\) and \(\eta\) over the same base \(B\), their Whitney sum is \(\xi\oplus\eta=\Delta^*(\xi\times\eta)\), whose fiber over \(b\) is the direct sum of the two fibers.