[1] rest-api-doc/rest_api.md at master · CrossRef/rest-api-doc (2017-04-20 17:58:37 +09:00) https://github.com/CrossRef/rest-api-doc/blob/master/rest_api.md

[2]

rest-api-doc/rest_api.md at master · CrossRef/rest-api-doc (2017-04-20 18:06:31 +09:00) https://github.com/CrossRef/rest-api-doc/blob/master/rest_api.md

If you need to tie your implementation to a specific major version of the API, you can do so by using content-negotiation and specifying the version of the API in the ACCEPT header as follows:
application/vnd.crossref-api-message+json; version=1.0