Bike 25¢ Bread Wagon 32¢ Ferry Boat $1 Sea Plane References and sources Notes Sources Scott catalog Further reading Agris, Joseph. The Transportation Coils and Other Plate Number Coils Issues. Houston, TX.: Eclectic Publishing, 1987 332p. Lawrence, Ken. "A Tribute to Transportation Coils." The American Philatelist. 105(6) (June 1991), p. 530-541. Winick, Les. The United States Transportation Coils. Florham Park, N.J.: The Washington Press, 1988 4p. Postage stamps of the United States