freitas et al. 2018, freitas et al. 2016, freitas et al. 2019, freitas et al. 2017, freitas et al. 2013, freitas et al. 2011, freitas et al. 2012, freitas et al. 2014, freitas et al. 2015, freitas et al. 2021, freitas et al. 2020
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