yeh, SOME people here know this book (the Original title is 'Resitance to Civil Government') in Germany.
I used it in my high-school-thesis [ ='Facharbeit'] about Martin Luther King who read that book too and I have a friend who was ready to go to jail instead of going to the army (that was in the beginning of the 90s, when it wasn't that easy to refuse this crap TOTALLY - to refuse even the 'Zivildienst', the kind of non-military-duty you were able to do instead of going to the army) - and he used quotes from it in his correspondence.
I don't know about Hesse's writings. Couldn't even bear to read the 'Steppenwolf'.
But anyways, Neither Thoreau nor Whitman are Common at all in G, are they?
Btw, concerning Whitman:
He lived at the same times as Thoreau (or R.W.Emerson - another one, unknown in G.) and was a great poet of NO BORDERS. Be it borders of believe, of gender, sex, age, race, of life or death, beauty or ugliness, a leave of grass or the whole of the stars - he knew of no borders between them or against them. He was Very Unique and one of the first to claim for a 'direct' style in poetry (here's a connection to Buk, though the 'direct' style at HIS times of course differs a LOT from what WE would call so).
In German there is an o.k.-translation of his main work 'Leaves of Grass' (= Grashalme) at Reclam. [forgett the 'insel'-edition!] but reading it, you'll Have to remember, it was written in another time!
Still ALL my Love goes to W.W. (ehm, AFTER my man Buk o/course.)