Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.
Agenda - A date-focused note taking app for both planning and documenting your projects.
Citavi - Citavi is a program for Microsoft Windows that manages literary references and organizes organizational knowledge.
Notepin - Extremely simple note-taking + blogging ✍️
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .
Bear - Bear.app is a note-taking and content writing app that helps you boost productivity with its intuitive tools.