Preanalytic and analytic factors affecting the measurement of haemoglobin concentration: impact on global estimates of anaemia prevalence oleh Sabine Braat, Beverley-Ann Biggs, Jena Derakhshani Hamadani, Leila M Larson, Mohammed Imrul Hasan, Sheikh Jamal Hossain, Sant-Rayn Pasricha, Kamija S Phiri, Martin N Mwangi, Fernando Estepa, Danielle Clucas