angl.„This object is unique and the origin of its surface chemistry is completely unclear“, Werner, K.; Rauch, T. (2011). „UV spectroscopy of the hot bare stellar core H1504+65 with the HST Cosmic Origins Spectrograph“. Astrophysics and Space Science. 335 (1): 121–24. Bibcode:2011Ap&SS.335..121W. doi:10.1007/s10509-011-0617-x.
harvard.edu
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angl.„This object is unique and the origin of its surface chemistry is completely unclear“, Werner, K.; Rauch, T. (2011). „UV spectroscopy of the hot bare stellar core H1504+65 with the HST Cosmic Origins Spectrograph“. Astrophysics and Space Science. 335 (1): 121–24. Bibcode:2011Ap&SS.335..121W. doi:10.1007/s10509-011-0617-x.