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   PR # 11136
    We propose to observe distant blazars to study the evolution of AGNs,
    especially of the central engines. Objects spectroscopied with Ginga
    and EXOSAT are limited to z=1.404. We selected high-z blazars to
    improve the results of the previous study toward high redshifted.
    Here we propose objects, up to z = 2.852, luminous enough to
    investigate the evolution with spectrum measurement.






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