If you want to deal with books and essays, then you
      should keep on reading here!

     zuzuku  -  Zugang zu Kunstwerken  -  access to art 
       offers the following information:

     Intoductery, understandable informational texts to the examination of intent and      aims with regard to the installation of sculptures in cities and rural areas. Not just      academic critical essays, but rather descriptions and texts directed at laymen.      Books, entries, articles about the creation and development of contemporary      sculptural works and their presentation.

      Sculpture Parks in Europe        the first printed survey, 2006 

      books, brochures, DVD (with a few contributions in English)

      lectures, essays (with a few contributions in English)