BibTex format
@article{Sivan:2021:10.1136/bmj.n853,
author = {Sivan, M and Rayner, C and Delaney, B},
doi = {10.1136/bmj.n853},
journal = {BMJ-BRITISH MEDICAL JOURNAL},
title = {Fresh evidence of the scale and scope of long covid},
url = {http://dx.doi.org/10.1136/bmj.n853},
volume = {373},
year = {2021}
}