Morisset, C. (2002). Are all annular planetary nebulae really closed shells? Universidad Nacional Autónoma de México.
Citazione stile Chigago Style (17a edizione)Morisset, C. Are All Annular Planetary Nebulae Really Closed Shells? Universidad Nacional Autónoma de México, 2002.
Citatione MLA (9a ed.)Morisset, C. Are All Annular Planetary Nebulae Really Closed Shells? Universidad Nacional Autónoma de México, 2002.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.