Advanced Linear Algebra
《Advanced Linear Algebra》 · 第 359-360 页 · Chapter 14「Bilinear Maps and Matrices. The Tensor Product」
A set function $f:U\times V\to W$ is bilinear if it is linear in both variables separately, that is, if $f(au+u',v)=af(u,v)+f(u',v)$ and $f(u,av+v')=af(u,v)+f(u,v')$.