Which blocks are these with small round knobs? I have few blocks remaining from the block set I got as a kid. It's not LEGO bricks, but I also couldn't find which block type are these and who is making them. Does anyone knows from looking the images who is making these and if they are still produced so I can buy them. 

Sorry if this is not right place to ask. Maybe you could point me to other place where I can ask.
I think this is Marklin plus,
a building system by Marklin which ran from 1973 till the end of the seventies





also see http://www.metallbaukasten.de/marklin/plus.html

thanks to the comment of Jan Windemuth for pointing me to Marklin