Robert Sparks. Explicit Subscriptions for the REFER Method. RFC, 7614:1-14, August 2015. [doi]
@article{rfc7614, title = {Explicit Subscriptions for the REFER Method}, author = {Robert Sparks}, year = {2015}, month = {August}, doi = {10.17487/RFC7614}, url = {https://doi.org/10.17487/RFC7614}, researchr = {https://researchr.org/publication/rfc7614}, cites = {0}, citedby = {0}, journal = {RFC}, volume = {7614}, pages = {1-14}, }