[1997] The four agreements

References
1 
@book{ruiz2010four,
  title={The Four Agreements: A Practical Guide to Personal Freedom},
  author={Ruiz, D.M. and Mills, J.},
  isbn={9781934408018},
  series={A Toltec Wisdom Book},
  url={https://books.google.co.cr/books?id=hzVxiw2DiOsC},
  year={2010},
  publisher={Amber-Allen Publishing, Incorporated}
}

In openlibrary.