“…Remark 8.2. MOR for pHODEs is discussed for instance in [4,5,23,37,38,40,45,58,71,81,95,96,112,118,142,166,176,177,199,201,205,208,[231][232][233]. Let us emphasize that for LTI systems, any passive system can be recast as a pH system, see [24,25].…”