HD 29/2/16. Green in Sherpa: Author's Pre-print: author can archive pre-print (ie pre-refereeing). Author's Post-print: author can archive post-print (ie final draft post-refereeing). Publisher's Version/PDF: author cannot archive publisher's version/PDF. General Conditions: Voluntary deposit by author of author's pre-print or author's post-print allowed on author's personal website or Institutional repository If mandated by a funding agency, the author's post-print may be deposited in any open access repository after an embargo period of between 0 months and 24 months (See linked document) Author's pre-print and Author's post-print not allowed on subject-based repository Must link to publisher version with DOI Publisher's version/PDF cannot be used Published source must be acknowledged with set statement Non-commercial. Full-text added (accepted v.), 15.3.16--MMM