Cone, C. D., "The Theory of Induced Lift and Minimum Induced Drag on
Non-Planar Lifting Systems," NASA TR-R-139, 1962.

De Young, J., "Induced Drag Ideal-Efficiency Factor of Arbitrary
Lateral-Vertical Wing Forms,"  NASA CR-3357, Dec. 1980

Gage, P., "New Approaches to Optimization in Aerospace Conceptual
Design," Ph.D. Thesis, Stanford University, Dec. 1994.

Gallman, J.W., Kroo, I., Smith, S.C., "Design Synthesis and Optimization
of Joined-Wing Transports," AIAA 90-3197, Sept. 1990.

Heyson, H. H., Roebe, G. D. and Fulton, C. L. "Theoretical Parametric 
Study of the Relative Advantages of Winglets and Wing-Tip Extensions," 
NASA TP 1020, 1977.

Jones,R.,Lasinski,T.,"Minimum Induced Drag of Wings with Winglets", 
NASA TM-81230, Sept. 1980.

Kroo, I., "A General Approach to Multiple Lifting Surface Analysis and
Design," AIAA 84-2507, Oct. 1984.

Lange, R.H., Cahill, J.F., et al., "Feasibility Study of the Transonic
Biplane Concept for Transport Aircraft Application," NASA CR 132462, 
Lockheed-Georgia Company, June 1974.

Letcher, J.S., "V-Wings and Diamond-Ring Wings of Minimum Induced Drag," 
J. of Aircraft, Vol. 9, No. 8. 1972.

Lundry, J. L. and Lissaman, P. B. S. , "Minimum Induced Drag on 
Non-planar Wings," J. Aircraft, Vol. 5, No. 1, 1968, pp. 17-21.

McMasters, J.H., Kroo, I.M., "Advanced Configurations for Very Large 
Subsonic Transport Airplanes," NASA Workshop on Potential Impacts of 
Advanced Aerodynamic Technology, portions published in NASA TM 109154,
Sept. 1994.

Munk, M. M., "The Minimum Induced Drag of Aerofoils,"  NACA  Report 121,

Smith, J. H. B., "Wing Tip Flows and Wing Devices (Symposium): 
Introductory Remarks," Aeronautical J., Dec. 1987, pp. 443-445.

Smith, S.C., "A Computational and Experimental Study of Nonlinear 
Aspects of Induced Drag," Ph.D. Thesis, Stanford University, June 1995.

van Dam, C.P., Induced Drag Characteristics of Crescent-Moon-Shaped 
Wings," J. of Aircraft, Vol. 24, No.2, 1987.

van Oossanen, P. , Joubert, P. N., "The Development of the Winged Keel
for Twelve-Metre Yachts," J. Fluid Mechanics, Vol. 173, 1986, pp. 55-71.

von Karman, T., Burgers, J.M., "General Aerodynamic Theory—Perfect 
Fluids,"  Vol. II of Aerodynamic Theory, W.F. Durand, ed.,  1935.

Wolkovitch, J., "The Joined Wing: An Overview," J. of Aircraft, 
March 1986.