The hybrid sink effect
N.H. Barton, Heredity 44 (1980) 277–278.

The fitness of hybrids between two chromosomal races of the grasshopper Podisma pedestris
N.H. Barton, Heredity 45 (1980) 47–59.

The structure and maintenance of hybrid zones as exemplified by Podisma pedestris
G. Hewitt, N.H. Barton, in:, R. Blackman, M. Ashburner (Eds.), Insect Cytogenetics, Wiley-Blackwell, 1980, pp. 149–170.