TY - JOUR
AU - Lindsey Smith
AU - Lawrence Aller
BT - The Astrophysical Journal
DA - Jan-08-1969
DO - 10.1086/150151
PY - 1969
EP - 1245
T2 - The Astrophysical Journal
TI - On the Classification of Emission-Line Spectra of Planetary Nuclei
UR - http://adsabs.harvard.edu/full/1969ApJ...157.1245S
VL - 157
SN - 0004-637X
ER -