Torres-Peimbert S, Arrieta A, Bautista M. Echelle spectroscopy of the nuclei of the highly collimated bipolar planetary nebulae M 2-9 and M 1-91. RevMexAA [Internet]. 2010 Nov. 22 [cited 2024 May 9];46(2). Available from: https://journals.unam.mx/index.php/revmexaa/article/view/20569