"Complication for simplicity's sake"
Article by Stewart Hine from 'Model Railways' November 1979
"Linked section control"
Articles by L. E. Carroll from 'Model Railway News':
"Linked Section Control in action“
Article by L. E. Carroll from 'Model Railway News' June 1958
"Signal-box Sub-sectioning"
Article by L. E. Carroll from 'Model Railway News' June 1956