Here are some books on the topic that have been mostly translated from German.
Cell Earth Books – Concave Earth Theory – Cellular Cosmogony – Skycentrism
Cellular Cosmogony or the Earth a Concave Sphere Part 1 and 2: The New Geodesy by Cyrus Teed and U.G. Morrow (1898)
Synopsis: concaveearth.net
Die Hohlwelttheorie (The Hollow World Theory) by Johannes Lang – English translation (1938)
Synopsis: concaveearth.net
The New Worldview The Hollow World Theory Part 1 and 2 – Johannes Lang – translated to English from German (1949)
Part 1 and 2: with illustrations (dark mode)
Download PDF (dark mode, with illustrations)
LANG JOHANNES : NEUPERT KARL – OUR KNOWLEDGE OF BEING (THE UNIVERSE IN THE GLOBE) (THE TRUE NATURE OF THE COSMOS) with illustrations translated (1926)
Supreme Harmony of Universe – Endospherical Field Theory by Paolo Emilio Amico Roxas – (Italian) translated, 1990
Paolo Emilio Amico-Roxas Endospherical Field Theory Diagrams Translated
Download Diagrams PDF
Synopsis: concaveearth.net
Spanish Blog: The "Supreme Harmony of the Universe" (Endospheric Field Theory, or "Cosmocentric System").
teoriaendosfericadelcampo.blogspot.com
See also: concaveearth.net
The Problem with Space and Time Paolo Emilio Amico-Roxas (1960)
THE PROBLEM OF SPACE AND THE CONCEPTION OF THE WORLD THE ENDOSPHERIC THEORY OF THE FIELD OR COSMOCENTRIC SYSTEM Roxas 1960
PDF source held in the research archive.
The Fight against the Copernican Worldview by Karl E. Neupert (1928)
GEOKOSMOS – WORLDVIEW OF THE FUTURE by Karl Neupert (1942)
Synopsis: concaveearth.net
World Puzzle Universe – Astronomy Under Cross-Examination by Alfred Müller 1949
The Three Story Universe of the Bible by Fritz Braun (1949)
Dark Mode translation with illustrations:
Synopsis: concaveearth.net
Turning Point in the World by Fritz Tauscher (1997)
Turning Point in the World by Fritz Tauscher – 1997 – Illustrations Translated (German)
Download PDF (German illustrations)
The Inner World of the Cosmos by Helmut I Diehl – 2003
Dark Mode JoeDubs translation: Download PDF
Black on White: Download PDF
Overview: concaveearth.net
The Biblical Worldview by Unknown (Dutch translation) – 1981
Overview: concaveearth.net
Geometry and Cosmos by Ernst Barthel (1939)
Heaven and Earth NotebookLM Model
Ask it questions, it'll give answers based on these books.