That looks like a factory service manual. I haven’t heard of bootleg hard copies. But that’s just one volume. There’ll be an engine volume, chassis and body volume, transmission volume, electrical volume, maintenance volume... maybe others like the model year introduction volume with information not found anywhere else. MB has about a foot tall stack of factory service manuals for any model of the vintage.

If you don’t mind printing a few pages or getting a PC dirty, you can use the engine section of this site - Model 124 Maintenance Manual Index

There is a 300E bible or two available for the engine section, and contrary to purists I found the Haynes W124 manual (not printed in US) was good enough for engine tasks. Don’t expect much on CIS function and troubleshooting beyond won’t start. FWIW, the Haynes book also covers Diesels which is useful when you graduate from the 300SEL to a 300SDL. Most of the factory volumes cover the SDL as well, you’ll just need the OM603 volume in place of the M103 volume.

Sixto
98 E320s sedan and wagon