Kritik der reinen Vernunft, "Reflexionen", Königlich Preussischen Akademie der Wissenschaften, Erich Adickes, difficulties, dating, precision, phase, security and probability. 1. Difficulty to locate the RR in relation to each phase due to the high variability of the RR’ dating. 2. Difficulty to locate the RR in relation to the place where they were written in.