Revert "Fix citation issues"

Description

Provide a concise explanation of the changes made in this merge request.

Related Issue(s)

• Closes #[feature issues]
• Fixes #[bug report issue]
• Resolves #[any other issues]

Other Changes

• [Mention refactoring, tests, etc.]

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Developer Checklist

• Code has been tested locally and/or in pipeline.
• (if applicable) documentation updated.
• (if applicable) impact of new dependencies reviewed and included in project.
• Merge conflicts resolved with the target branch.

Additional Notes

Add any information reviewers should focus on, e.g., specific files, functions, or changes of interest.

docs/assets/bibtex/propulsion_design_literature.bib

-@Misc{Pet13,
-  title = {Regression line from LTH-Data},
-  author = {Fabian Peter},
-  year = {2013},
-  note = {For A319-100, A320-200, A321-200, A340-300B, A300-600R, A310-300, A330-200 see Excel file "sheet real_reduziert" on RWTH Aachen ILR-Server: \textbackslash\11\_MICADO\04-Descriptions\massEstimation\engine\[engineWeightMethods.xlsx] (stand von Fabian Peter 2012)}
-}
-
-@misc{Ata10,
-  author = {Atanasov, Georgi},
-  year = {2010},
-  title = {Methodische Entwicklung von Konzepten zur Antriebsintegration im Flugzeugentwurf},
-  howpublished = {Diplomarbeit, RWTH Aachen University, Aachen, Germany}
-}