1. Avezova GS, Kosimova SM. Frequently ill children: prevalence and risk factors. European Research. 2017;5(28):79–80. (In Russ.) Available at: https://cyberleninka.ru/article/n/chasto-boleyuschie-deti-rasprostranennost-i-faktory-riska.
2. Abramova NA, Savenkova MS. The role of social and environmental factors in forming a group of sickly children from socially-secured families in Moscow. Children Infections. 2013;(4):52–57. (In Russ.) Available at: https://cyberleninka.ru/article/n/rol-sotsialnyh-i-ekologicheskih-faktorovv-formirovanii-gruppy-chasto-boleyuschih-detey-v-sotsialno-blagopoluchnyh-semyah-g-moskvy?ysclid=lp5g8wp73b605604048.
3. Romantsov MG, Melnikova IYu. Often long-term ill children: not only a medical, but also a psychological and pedagogical problem. Problems of pedagogy. 2016;9(20):5–12. (In Russ.) Available at: https://cyberleninka.ru/article/n/chasto-boleyuschie-deti-ne-tolko-meditsinskaya-no-ipsihologo-pedagogicheskaya-problema?ysclid=lp5gbb20nb952854780.
4. Samsygina GA. Frequently ill children: problems of pathogenesis, diagnosis and therapy. Pediatriya – Zhurnal im G.N. Speranskogo. 2005;(1):66–73. (In Russ.) Available at: https://cyberleninka.ru/article/n/chasto-boleyuschie-deti-problemy-patogeneza-diagnostiki-i-terapii?ysclid=lp5gdiw1xo301312817.
5. Nikolaeva AYu, Shamsheva OV. Ways to optimize the immune response to vaccination in frequently ill children. Children Infections. 2004;4:38–40. (In Russ.) Available at: https://cyberleninka.ru/article/n/puti-optimizatsii-immunnogo-otveta-na-vaktsinatsiyu-u-chasto-boleyuschih-detey?ysclid=lp5geaptby310280283.