What does PPN stand for?
PPN stands for "Proto-Planetary Nebula"
How to abbreviate "Proto-Planetary Nebula"?
"Proto-Planetary Nebula" can be abbreviated as PPN
What is the meaning of PPN abbreviation?
The meaning of PPN abbreviation is "Proto-Planetary Nebula"
What does PPN mean?
PPN as abbreviation means "Proto-Planetary Nebula"