Omission of cross-references between related articles.
D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D008168:Lung / Q000098:blood supply* / Q000503:physiopathology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012892:Sleep Deprivation / Q000503:physiopathology*