The Mundaka Upanishad, which is also called Mundakopanishad is one of the earlier main, i.e. Primary Upanishads. It is associated with the Atharva Veda.
Though it is a very short text, this classic Vedic scripture is time immemorial and is meant to be read, re-read and studied to understand the true nature of our consciousness and existence.
In addition to the text of Mundaka Upanishad, this book contains an introduction to the very concept of Upanishads, lists out the main upanishads and also provides an introduction to the Mundaka Upanishad.