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E-print: https://arxiv.org/abs/1901.05332
E-print: https://arxiv.org/abs/1806.07791
E-print: https://arxiv.org/abs/1811.05230
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E-print: https://arxiv.org/abs/1702.08029
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E-print: http://arxiv.org/abs/1511.07359v2