1. USSR Inventor's Certificate No. 164,289; Otkrytiya, No. 15 (1964).
2. USSR Inventor's Certificate No. 176,912; Otkrytiya, No. 24 (1965).
3. USSR Inventor's Certificate No. 180,605; Otkrytiya, No. 8 (1966).
4. USSR Inventor's Certificate No. 201,416; Otkrytiya, No. 18 (1967).
5. USSR Inventor's Certificate No. 201,417; Otkrytiya, No. 18 (1967).