The Help page of the Arolsen Archives includes information about how to cite their records:
When you cite documents, always give the following information:
[Title of the document], [Sub-collection number]/[Doc-ID]/ITS Digital Archive, Arolsen Archives
Example: Report on Conferences on Unaccompanied Children, 1946, 6.1.2/82489042/ITS Digital Archive, Arolsen Archives
However, I'm having a hard time figuring out what the "title of the document" actually is, or where to look for the "sub-collection number".
The record in question is a passenger manifest showing my father-in-law's brother (and FIL as sponsor/destination), which the search engine will only cough up if I look for the mistranscription that's in their index: https://collections.arolsen-archives.org/en/archive/81740087/?p=1&s=Szent-Gyogyi%20Gyula&doc_id=81740087
I see from the URL that the "doc-ID" must be the (unselectable) number that's between the image and the thumbnails (81740087), leaving the thing labeled "Reference Code" (1384075) as the only other number on the page. Is that somehow the "sub-collection number"? And is the title "Correspondence and nominal roles, done at Belgrad: transport by airplane (MIGEN H-12892); transit countries and final destinations: USA", or is it "Registrations and Files of Displaced Persons, Children and Missing Persons", or something else?