“…There have been several valuable reviews of PNe over the years, such as those by Kaler (1985), Kwok (1994), Kwitter et al (2014), andZijlstra (2015). Recent IAU Symposia on PNe are Barlow & Méndez (2006); Manchado et al (2012), and Liu et al (2016). Books and monographs concentrating on PNe include Aller & Liller (1968), Aller (1971), Pottasch (1983), Aller (1984), Gurzadyan (1997), Kwok (2000), and Osterbrock & Ferland (2006).…”