Springer Nature Experiments has a standalone Stanza now for EZProxy. Please find the most up to date version of this stanza on the OCLC Stanza page.
For Reference the Stanza below was updated on 31 May 2019:
Title Springer Nature Experiments (updated 20190531) URL https://experiments.springernature.com HJ http://experiments.springernature.com HJ springernature.com DJ springernature.com
For hosted proxy service customers in the US using self-service this is the record to place in your Include File:
IncludeFile databases/springerprotocols.txt