books.google.co.uk - Traces the development of the omnibus through the horse-drawn era to that of mechanical propulsion, when, after experiments with steam and electric battery units, the petrol engine reigned supreme until just before the Second World War....http://books.google.co.uk/books/about/Old_Buses.html?id=rkr-qjm12NMC&utm_source=gb-gplus-shareOld Buses
