Green in Sherpa: Author's Pre-print: 	green tick  author can archive pre-print (ie pre-refereeing)
Author's Post-print: 	green tick  author can archive post-print (ie final draft post-refereeing)
Publisher's Version/PDF: 	green tick  author can archive publisher's version/PDF
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    On open access repositories
    Authors retain copyright
    Creative Commons Attribution License
    Published source must be acknowledged
    Publisher's version/PDF may be used
    Set statement to accompany [This Document is Protected by copyright and was first published by Frontiers. All rights reserved. it is reproduced with permission.]
    Articles are placed in PubMed Central immediately on behalf of authors.. --
Full-text added 6.10.17-MMM