Henry David Thoreau & Fyodor Dostoevsky 
The Existential Literature Collection [EPUB ebook] 

Existentialism is a movement in philosophy and literature that emphasizes individual existence, freedom and choice. It holds that, as there is no God or any other transcendent force, the only way to counter this nothingness (and hence to find meaning in life) is by embracing existence.
The Existential Literature Collection features:
FEAR AND TREMBLING, by Soren Kierkegaard
MANIFESTO OF THE COMMUNIST PARTY, by Karl Marx and Friedrich Engels
ON THE DUTY OF CIVIL DISOBEDIENCE, by Henry David Thoreau
NOTES FROM THE UNDERGROUND, by Fyodor Dostoyevsky
BEYOND GOOD AND EVIL, by Friedrich Nietzsche
THE WILL TO BELIEVE, by William James
IS LIFE WORTH LIVING?, by William James
HEART OF DARKNESS, by Joseph Conrad
I AM MUCH TOO ALONE IN THIS WORLD, YET NOT ALONE, by Rainer Maria Rilke
and
THE TRIAL, by Franz Kafka