Hoogendijk EO, Onder G, Smalbil L, Vetrano DL, Hirdes JP, Howard EP, Morris JN, Fialová D, Szczerbi?ska K, Kooijmans ECM et al..  2023.  Optimising the care for older persons with complex chronic conditions in home care and nursing homes: design and protocol of I-CARE4OLD, an observational study using real-world data. BMJ Open. 13(6):e072399.