Stalker's Diary 3 is a diary entry that can be collected in Metro Exodus' The Two Colonels DLC.
Location[]
The Two Colonels: After fighting the blind one and falling down an elevator shaft, walk up the scaffolding to your immediate right. The note will be on the ground, right in front of the tunnel.
Transcript[]
Good news: we reached the archive. Bad news: the blind giants seem to have made it their lair. Luckily, there was nobody home, so we at least took a look around...
The shelves are trashed, the maps are all in heaps, it's going to take us at least a few days to make anything out of this mess, and the new tenants could come back at any moment. Something tells me they aren't going to be all too happy to find us cataloging the archives without their permission.
To make matters worse, radiation is off the scale in the archive. We spend five minutes there, then took a month's share of green stuff each, and I'm still feeling queasy...
I'll have to ask the Colonel to arrange a bonus for us all, otherwise we'll all keep glowing in the dark for months.
Of course, we grabbed as many maps as we could carry while we were there, let the guys at HQ sort them out. That, at least, would give them something to do.
In any case, the mission is complete as it could ever be, and if anyone thinks he could do better, he's welcome to try! I, for one, am not setting a foot in that grave ever again if I can help it!