This helmet has been used by the Belgian paratroopers. I don't have a lot of information about it and I haven't found any markings inside. The liner looks a lot like the one used in the French model F-1 series 1 helmets.
The Bulgarian Model 36A looks like the German Model 35. I found information saying these helmets were also manufactured in Germany. 'This helmet has been reconditioned after the WW2. The paint is no longer the dark green colour it had before the war. The liner is also post-war maybe some day I get lucky and I will find myself a M36A in pre-war condition. The M36A has a rolled edge like the German M35 and M40. see picture 8 for a close up of the edge.