Knoppix 4.0

[sas-seb]

found another http version of the DE dvd.
its split into 8 files.

http://tyge.sslug.dk/knoppix/KNOPPIX_V4.0_split/

Could you tell me please how to burn these 8 files onto 1 DVD+R?
How to join these 8 splitted files in 1 file *.iso?