1. BECK, V, OPTIK 53: 237 (1979).
2. Beck, V., Proceedings of the 35th Annual Meeting of the Electron Microscopy Society of America: 30 (1977).
3. BLACK, G, SPHERICAL ABERRATION AND THE INFORMATION CONTENT OF OPTICAL IMAGES, PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL AND PHYSICAL SCIENCES 239: 522 (1957).
4. COWLEY, J.M., ULTRAMICROSCOPY 3: 433 (1979).
5. CREWE, A.V., JOURNAL DE MICROSCOPIE 2: 369 (1963).