Leitz Informational Book "Optical Performance in Microscopy" digital download or on CD (shipping extra) featuring Adobe PDF file.  There are a total of 32 pages containing color pictures, illustrations and product numbers about the construction & proper use of Leitz objectives. The objective types covered are:

1. Achromat objectives
2. Semiapochromatic objectives
3. Apochromatic objectives
4. Eyepieces

The book is labeled on the back: I/86/FDX/w and the catalog insert sheet is: III/86/FLX/w.