https://link.springer.com/content/pdf/10.1007%2Fs00233-007-0726-6.pdf (Verlagsversion)
Haji, A., & Radl, A. (2007). A semigroup approach to queueing systems. Semigroup Forum, 75(3), 610-624. doi:10.1007/s00233-007-0726-6.