Item drop system - Official TF2 Wiki

Capo's Capper - Official TF2 Wiki

Steam Community :: Guide :: The Item Drop System (TF2)

Mann Co. Supply Crate - Official TF2 Wiki

Community Spy strategy - Official TF2 Wiki

Direct Hit, Team Fortress Wiki

Medic, Team Fortress Wiki

Pyromancer's Mask, Wiki

Система получения предметов - Official TF2 Wiki

The wiki has updated the DT2 boss pages for estimated rates of the drops : r/2007scape

I have recently got this neat lad as a drop,what was your most expensive drop? : r/tf2

Loot box - Wikipedia

Steam Community :: Guide :: The Item Drop System (TF2)

Winger, Team Fortress Wiki

Cheater's Lament - Official TF2 Wiki

List of retired items - Official TF2 Wiki