Librería Samer Atenea
Kálamo Books
Librería Elías (Asturias)
Librería Kolima (Madrid)
Librería Proteo (Málaga)
Written in the 1960s for the sexual fiction market, this book features 'case studies of the swinging lifestyle' -- billed as 'raw, bold, intimate, and graphic sexual exposes!' -- though quite mild by modern standards.