Schonmann, Y, Mansfield, KE, Smeeth, L, Langan, S and Nitsch, D (2019). Clinical Codelist - Smoking - Read Codes. [Data Collection]. London School of Hygiene & Tropical Medicine, London, United Kingdom. https://doi.org/10.17037/DATA.00001222.

Mansfield, KE, Schmidt, SAJ, Darvalics, B, Mulick, A, Abuabara, K, Wong, A, Sørensen, HT, Smeeth, L, Bhaskaran, K, Silva, I, Silverwood, R and Langan, S (2019). Clinical Codelist - Smoking - Read Codes. [Data Collection]. London School of Hygiene & Tropical Medicine, London, United Kingdom. https://doi.org/10.17037/DATA.00001285.