Hans-Georg,
The Missionsanstalt Hermannsburg has an Archiv that is very helpful.
They also have a bookstore. I have corresponded with them over the years and
visited them for a few days in 1991. Through them I was able to purchase a
complete used set of the four volume Hannover Missionsgeschichte by Dr. Georg
Haccius that was published in the first decade of the last century. I was also
able to obtain a copy of a Lebensbeschreibung of my great-great grandfather who
was a student there from 1863 to 1867. They can probably help you in your
quest and no doubt have a copy of the work you mentioned.
Mit freundlichen Gruessen,
Gary Lee Beard
Bellevue, Washington