MyNotex is a free software for Linux useful to take and to manage your notes, including a large number of notes. Notes can be gathered under different subjects, titles, dates and keyword tags, making it easy to access and put order to all of your notes.
Giving MyNotex a test drive was easy thanks to a DEB file available on their download page. I found the program easy to use and see room for improvement. The software can manage bullets and numbered lists, bold font, italic, underline, strike-through and more. After creating single file in MyNotex it will contain all of your various subjects and notes.
Good luck Massimo in your endevours and we look forward to any updates to MyNotex!