From 2014 we have kept a copy of the most recent version of the
manuscript on the home page of Olof Staffans
(http://www.abo.fi/~staffans). The most recent copy is from 2017.
We have been citing this book in our papers, sayings
something like "for more details, see our book, Sections so and so".
So has many others. Because of this, there already exists a number of
citations to this book in the literature, with preliminary titles
"Linear Stationary Systems in Continuous Time" and "Linear Stationary
Input/State/Output and State/Signal Systems".
Version 0, March 3, 2014.
Version 1, April 9, 2014.
Version 2, January 17, 2015.
Version 3, January 17, 2016.
Version 4, January 17, 2017