I only googled PG not PG +books. As the context was poor quality e-books, I thought maybe it was some torrent site like TPB
perhaps wikipedia needs an edit
PG
From Wikipedia, the free encyclopedia
Look up pg, Pg, or PG in Wiktionary, the free dictionary.
PG or P.G. may refer to:
PG, abbreviation for "Parental Guidance" by British Board of Film Classification or "Parental Guidance suggested" by Motion Picture Association of America film rating system
Business and Products[edit]
P.G. Cigars, brand of cigars by its owner Paul Garmirian
PG Tips, a brand of tea
Procter & Gamble, a consumer goods company
....
project guthenburg does not even make it into other uses...
Other uses[edit]
Page (paper)
Parental Guidance, a designation in various motion picture rating systems
MPAA Rated PG
Patrologia Graeca, a collection of writings by the Christian Church Fathers
pg (Unix), a Unix system command
Point guard, one of the five positions in basketball
Policy Governance, a system for organizational governance
Postgraduate
Power Girl, a DC Comics character
Proto-Germanic
PG, a truncation of Panzergewinde, which in turn is a contraction of the German Stahlpanzerrohrgewinde (steel conduit thread), a type of thread used for Cable glands.
PG Perfetto Gracia
iPhrothiya yeGolide (PG) - South African Military Decoration