Revert "Fix citation issues"

.gitlab-ci.yml

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docs/assets/bibtex/propulsion_design_literature.bib

...entation/analysis/ecological_assessment/basic-concepts.md

...cumentation/analysis/ecological_assessment/literature.bib

docs/documentation/analysis/index.md

docs/documentation/overview.md

...tation/sizing/propulsion_design/engineering_principles.md

mkdocs.yml