1. Test flights of the NASA ultra-long duration balloon
2. Design considerations and practical results with long duration systems for manned world flights
3. 3Smalley, J. H. "Determination of the shape of a free balloon," Scientific report no. 2, afrl 64-374, Air Force Cambridge Research Labovatories, Bedford, MA, Dec. 1963.
4. 4Nishimura, J., Okai, S. and Ogita, N. (). "On the natural shape of the plastic balloon", International Symposium on Space Technology and Science, 5, 446-450, 1963.
5. 5Rand, J. L. "Shape and stress of an ascending balloon," Report no. wii-9936-fr-01, NASA/Jet Propustion Lab, Pasadena, CA, 26June 1987.