You mean this book by Leroux and Labelle? http://bergeron.math.uqam.ca/species/ http://bergeron.math.uqam.ca/species/ (First 3 chapters: http://bergeron.math.u

You mean this book by Leroux and Labelle? http://bergeron.math.uqam.ca/species/ http://bergeron.math.uqam.ca/species/ (First 3 chapters: http://bergeron.math.uqam.ca/wp-content/uploads/2013/11/book.pdf http://bergeron.math.uqam.ca/wp-content/uploads/2013/11/book...) "Enumerative Combinatorics" is a different book by a different author (Richard P. Stanley, https://en.wikipedia.org/wiki/Richard_P._Stanley https://en.wikipedia.org/wiki/Richard_P._Stanley).