 Humean better best system accounts of cp-laws are presented in Cohen and Callender (2009, 2010), Schrenk (2007a, 2014), and Unterhuber (2014). Wheeler (2018: chapter 3.2) gives an accessible brief exposition of various versions; and Reutlinger (2009) and Backmann and Reutlinger (2014) provide a critical discussion. 