General question: That book I bought is called "Die neue Harmonielehre", the one you recommended me.(I also bought "Die Rhythmiklehre", thanks for these 2 books, really great to work with them!)
Anyway, I finished the interval chapter and everything there is clear to me, also the next few pages I´m reading at the moment(triads). So but I´m still learning these intervals, because I feel that I should know them quite immediately after I look at them. Is this really necessary or is it enough when I have to think for them for 5-10 seconds.