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The criterion of infrared excess has been used to obtain a first candidate list of non-radio QSOs in a field centered at 15h, +35°. Spectrographic data for objects with infrared excesses, chosen from a complete catalogue of blue objects to B 19.4 mag, show that fifteen objects, out of sixteen candidates observed, have emission lines characteristic of QSOs. Redshifts are given for fourteen of the objects. The surface density of QSOs in this field, when compared with the results of a survey to a brighter limiting magnitude for the PilL field D36m, +6°, shows that the number of objects continues to increase quite steeply going to fainter magnitudes
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Braccesi et al. (1968) studied this question.
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