It can be a rather solitary venture, and the pickings are relatively thin. The Patek Philippe library will be resourceful, but I've found delving into the national archives of Brazil, contemporary lifestyle magazines, the work of artists and photographers, and even trade journals, to be quite useful. It helps to be an amateur historian too, and there's plenty of literature to draw on. Knowing a little Portuguese also goes a long way too. I'll pull something together in due course.