1. General information on the Third Edition of the International Patent Classification,1979
2. WIPO Doc. PCPI/P 49/79 Rev.6 Ann. 23.
3. Consistency of use of the International Patent Classification;Carpenter;International Classification,1978
4. Reasons for inconsistencies in the use of the International Patent Classification;Eisenschitz;International Classification,1979
5. WIPO Doc. PCPI/P 49/79 Ann. 2.