Detection
From Tardis Wiki, the free Doctor Who reference
Gustave Lytton wished to avoid detection and so relayed his distress call. (TV: Attack of the Cybermen [+]Loading...["Attack of the Cybermen (TV story)"])
By 2007, a poster by BNFL in Deffry Vale High School included information on detecting radiation. (TV: School Reunion [+]Loading...["School Reunion (TV story)"])