My 1937 civilian bike has no holder for handbook in its civilian toolbox and no chain but (unlike the rest of the bike) the PO took it off and repainted it - losing the original suitcase-type lock in the process.
I do have a military bike rider's handbook (with owner's name) so if you are interested I could measure it and you can say if it would fit whatever holder you have. It's a small black card covered booklet with all the servicing information.