13.5.15-MMM Yellow in Sherpa: Author can archive pre-print (ie pre-refereeing) Subject to Restrictions below, author can archive post-print (ie final draft post-refereeing) Subject to Restrictions below, author can archive publisher's version/PDF, Restrictions: 6 months embargo General Conditions: Cannot archive until publication Author's pre-print and Author's post-print on author's personal website, institutional repository or subject repository Publisher copyright and source must be acknowledged Must link to journal webpage and /or DOI Publisher's version/PDF cannot be used, unless covered by funding agency rules Authors covered by funding agency rules, may post the Publisher's Version/PDF in subject repositories after a 6 months embargo - Published in January 2015, Added embargo expired date, 15.5.15-MMM