Given a short bio of a person, find the minimal text span containing the date of birth of the person. The output must be the minimal text span that contains the birth date, month and year as long as they are present. For instance, given a bio like 'I was born on 27th of Decemeber 1990, and graduated high school on 23rd October 2008.' the output should be '27th of December 1990'.

Harrison Ford was born at the Swedish Covenant Hospital in Chicago, Illinois, on July 13, 1942, to former radio actress Dorothy (née Nidelman) and advertising executive and former actor John William "Christopher" Ford
July 13, 1942