http://kopeltech.com/bbs/data/3_2/XR_015.pdf
http://www.kopeltech.com/manual/XR-50.pdf
http://www.kopeltech.com/manual/kr-5.pdf
http://www.kopeltech.com/manual/krb-5.pdf
http://www.kopeltech.com/manual/kr-770.pdf
http://www.kopeltech.com/manual/kr-700.pdf