Barría, D.; Kimeswenger, S. (October 2018). "HST/WFPC2 imaging analysis and cloudy modelling of the multiple-shell planetary nebulae NGC 3242, NGC 6826, and NGC 7662". Monthly Notices of the Royal Astronomical Society. 480 (2): 1626–1638. arXiv:1807.01787. Bibcode:2018MNRAS.480.1626B. doi:10.1093/mnras/sty1796.
Barría, D.; Kimeswenger, S. (October 2018). "HST/WFPC2 imaging analysis and cloudy modelling of the multiple-shell planetary nebulae NGC 3242, NGC 6826, and NGC 7662". Monthly Notices of the Royal Astronomical Society. 480 (2): 1626–1638. arXiv:1807.01787. Bibcode:2018MNRAS.480.1626B. doi:10.1093/mnras/sty1796.
Barría, D.; Kimeswenger, S. (October 2018). "HST/WFPC2 imaging analysis and cloudy modelling of the multiple-shell planetary nebulae NGC 3242, NGC 6826, and NGC 7662". Monthly Notices of the Royal Astronomical Society. 480 (2): 1626–1638. arXiv:1807.01787. Bibcode:2018MNRAS.480.1626B. doi:10.1093/mnras/sty1796.