The Irish clans in the show speak Shelta, an Irish nomadic language that is derived from Irish Gaelic, English, Roma, and some other languages. The name of the language is allegedly derived from Irish "siúlta", "of walking". The episode name means "strangers" in the Shelta language.
The book which Detective Goren cites as Prof. Malcolm Bryce's inspiration for investigating modern-day gypsy "Travelers" is an actual text. "The Jukes: A Study in Crime, Pauperism, Disease, and Heredity," by American sociologist Richard Louis Dugdale (1841-1883), was first published in 1877 and went through numerous editions, spurring intense debate on the topic of "nature vs. nurture" in the lives of career criminals.