An Observed Contrast of NGC 1501 with the Specified Emission-Line Intensity Ratio Tamura, S. ; Malasan, H. L. ; Yamasaki, A. ; Hashimoto, O. ; Kambe, E. ; Takeuti, M. Abstract Publication: Asymmetrical Planetary Nebulae Pub Date: 1995 Bibcode: 1995AnIPS..11..163T