Student Friendly Quantum Field Theory is available through most retail book outlets, online and local, throughout the world.
Be sure to order the latest version, as it incorporates all the many errata corrections reported and pedagogic improvements suggested by readers of earlier versions. See version information for details.
The link for the second edition at Amazon.com is Amazon 2nd ed SFQFT
CAUTION: Take care not to buy the 1st edition, which Amazon is still trying to sell..