The Phenomenology of Mind or Phenomenology of Spirit (German: Phänomenologie des Geistes), originally published in 1807, was the first major philosophical work by Georg Wilhelm Friedrich Hegel, and still the most influential.
Like much of Hegel's writing, it is notoriously difficult, but can be described as an account of the necessary steps in the development of thought. It's description of the relationship between self and other is significant for establishing the irreducibly social nature of consciousness.
The Phenomenology of Mind at online books stores
Free online texts
Marxists Internet Archive: Hegel's Phenomenology of Mind, translated by Terry Pinkard.
University of Adelaide/Internet Archive: The Phenomenology of Mind, translated by J.B. Baillie. EPUB, HTML and MOBI formats.
Wikisource: The Phenomenology of Mind, translated by James Black Baillie. Currently introduction only. HTML and other formats.
Deutsches Textarchiv: Die Phänomenologie des Geistes. HTML, Text, XML formats.
Gutenberg: Phänomenologie des Geistes. EPUB, HTML, MOBI and PDF formats.
Internet Archive: System der Wissenschaft - Erster Theil, die Phänomenologie des Geistes. EPUB, MOBI, PDF and TXT formats.
Librivox: The Phenomenology of Mind - public domain audiobook.
Stanford Encyclopedia of Philosophy: George Wilhelm Friedrich Hegel.
YouTube: Half Hour Hegel - The Complete Phenomenology of Spirit, by Gregory B. Sadler.
Further reading at Tom's Learning Notes
Immanuel Kant: The Critique of Pure Reason - Philosophers still debate whether Hegel's approach is consistent with Kant, a return to pre-Kantian metaphysics, or an attempt to strike out in a different direction.
Sophocles: Antigone - considered by Hegel as reflecting a contradiction between familial and political life that cannot be overcome within the limits of pagan classical thought.