PT - JOURNAL ARTICLE AU - de Lusignan, Simon TI - In this issue: Ontologies a key concept in informatics and key for open definition of cases, exposures and outcome measures AID - 10.14236/jhi.v22i2.170 DP - 2015 Apr 01 TA - BMJ Health & Care Informatics PG - i--v VI - 22 IP - 2 4099 - http://informatics.bmj.com/content/22/2/i.short 4100 - http://informatics.bmj.com/content/22/2/i.full