BibTex format
@article{Hurst:2021:10.1136/bmjopen-2021-055435,
author = {Hurst, EA and Mellanby, RJ and Handel, I and Griffith, DM and Rossi, AG and Walsh, TS and Shankar-Hari, M and Dunning, J and Homer, NZ and Denham, SG and Devine, K and Holloway, PA and Moore, SC and Thwaites, RS and Samanta, RJ and Summers, C and Hardwick, HE and Oosthuyzen, W and Turtle, L and Semple, MG and Openshaw, PJM and Baillie, JK and Russell, CD},
doi = {10.1136/bmjopen-2021-055435},
journal = {BMJ Open},
pages = {1--11},
title = {Vitamin D insufficiency in COVID-19 and influenza A, and critical illness survivors: a cross-sectional study},
url = {http://dx.doi.org/10.1136/bmjopen-2021-055435},
volume = {11},
year = {2021}
}