Hello Frederik,
the following books might be steps to get deeper into music, theorie, harmonie counterpoint, composition. I used them during my studium. I could give you a list of books about all this from beginners to advanced but they are all in german. It is of course impossible to list the vast literature on historical and new music theory published in the past few decades. Hugo Riemann— whose theories have enjoyed a remarkable renaissance among more formally-minded music theorists in the United States— has received renewed attention.
Wikipedia: His best known works are the famous Musiklexikon, a complete dictionary of music and musicians, the Handbuch der Harmonielehre, a work on the study of harmony, and the Lehrbuch des Contrapunkts, a similar work on counterpoint, all of which have been translated into English. One of his inventions, the Tonnetz, is the predecessor of the modern idea of pitch spaces.
He has written many other works which indicate an encyclopaedic knowledge of music in all its branches. He is held in the highest possible esteem by German musical authorities.
other books:
In English
all from:
Schoenberg, Arnold.
Style and Idea. Selected Writings.
Berkely: University of California Press, 1984.
Fundamentals of Musical Composition.
Strang, Gerald. Ed.
London: Faber and Faber, 1967.
Structural Functions of Harmony.
Stein, Leonard. Ed.
London: Faber and Faber, 1983.
In German
Harmonielehre.
Wien: Universal Edition, 1966.
You also could ask at the music highschool in Amsterdam if you are allowed to visit their library or ask at the university.
Anyway, here are 2 links which might be useful for you:
Solomon's Music Theory
Music 4113 X1 Special Studies in Music Theory: Seminar in Music Analysis
For me the most important thing beside the knowledge of all this is always the musical idea and if it´s possible to take the time to work on it and think about it. Investigation on the subject. Otherwise how can it be that musicians who had no idea of theory and harmonie came up with the most brilliant and incredible music of all genres. And at least: Listen to Bach, listen to Miles Davis!
You know what I mean, don´t you?
That´s for now, thanks for the question and the interest.
All the best,
Torsten Brandes