How it goes in practice.
Gather the sources
Drop the PDFs and Word files into a project folder. Jotura writes a Markdown copy of each one for search and keeps the original beside it.
Read and highlight
Read the longer books on your Android phone. Each highlight and its comment lands in a note for that book, ready to quote.
Write the notes
Write a note per idea and link it to its sources by typing [[. Tag notes by theme, such as #method or #open-question.
Find it again
Search the whole folder by word, or by meaning on the desktop, to find the note you only half remember.