If you follow them back through the books ...
The reference you gave
[1] has a note, "GB 685" -- the old book, p 685. Go there
[2], and you find another note -- they came from "1040" 1922. Look up page 1040
[3], and you see that Elsa Katarina came from Stockholm, Kungsholm 1920-12-11.
Look up the marriage book of Kungsholm, on the date you have (1920-11-20), and you find they were indeed married there
[4] on that date -- and also a reference to the banns book ("Lysningsboken")
[5], which has even more information
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Make paste-able source references with the Copy menu (the icon, almost all the way to the right, looks like two stacked documents), and use the "Copy Anbytarforum-link" menu item. An old post of mine about this:
https://forum.rotter.se/index.php?topic=162252.0.
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[1] Nyköpings Sankt Nicolai (D) AIIa:20 (1927-1930) Bild 3080 / Sida 652 (AID:
v164526.b3080.s652, NAD:
SE/ULA/11128)
[2] Nyköpings Sankt Nicolai (D) AIIa:16 (1920-1926) Bild 3410 / Sida 685 (AID:
v164520.b3410.s685, NAD:
SE/ULA/11128)
[3] Nyköpings Sankt Nicolai (D) AIIa:17b (1920-1926) Bild 890 / Sida 1040 (AID:
v164522.b890.s1040, NAD:
SE/ULA/11128)
[4] Kungsholm (A, AB) EII:9 (1917-1921) Bild 2160 / Sida 212 (AID:
v254823.b2160.s212, NAD:
SE/SSA/0011), #380/1920
[5] Kungsholm (A, AB) EI:31 (1920) Bild 1900 / Sida 373 (AID:
v254791.b1900.s373, NAD:
SE/SSA/0011), #373/1920