1. Caspar W (1977) A new surgical procedure for lumbar disc herniation causing less tissue damage through a microsurgical approach. Advances in Neurosurgery 4: 74–77. Springer, Berlin Heidelberg New York
2. Caspar W, Loew F (1977) Die mikrochirurgische Operation des lumbalen Bandscheibenvorfalles. Dtsch Ärzteblatt 13: 863–868
3. David MG (1985) Efficacy of chymopapain chemonucleolysis: A long term review of 105 patients. J Neurosurgery 62: 662–666
4. de Divititis E, Spaziante R, Stella L (1979) Some technical modification of surgical treatment of lumbar disc lesions. Neurochirurgia (Stuttg) 22: 95–98
5. Gilsbach J, Eggert HR, Weeger W (1979) Microsurgical operation for herniated lumbar disc. AESCULAP own publication