end-to-end delay proof

1. Reich, Burk, 扫盲的论文

2. Boxma的论文，LAA 不对。

3. Wolf, Melamed Whitt, WLAA, ASTA.

4. ASTA PF-form, 娱乐性质。

https://math.stackexchange.com/questions/3855169/joint-laplace-transform-is-product-of-laplace-transforms-then-independence#:~:text=Let X and Y be ,p%2Cq%E2%88%88R%2B.