I wanted to ask if you have any specific paper calendars or planners which cover an academic year (October - September) and which you can recommend for PhD students? Thanks a lot!
This may not seem relevant, but it is something I've found very useful/indispensible over the years, both for studying and for teaching. I actually required some of my students to use them.
It is called a Hipster PDA, which is nothing more than a few index cards and a spring clip to hold them together. I discussed it in answer to another question at CSEducators here. See that link for a fuller description and a further link to pictures, etc.
The reason it is so valuable is that it is both simple and flexible. It is easy to carry everywhere and can be rearranged as needed. Cards can be added and discarded. Valuable cards can be saved in a card box. You can use it for class notes as well as planning. You can use it to take quick notes in meetings or to jot down email or phone numbers, etc.
One advantage of it as a note taking device is that it forces you to condense what you hear in lecture rather than to try to capture everything. This makes your brain work harder, which aids learning.
At the end of a class, for example, you can make a card listing the two or three most important ideas from that class. Review that card at the beginning of the next.
Another advantage is that you are writing the notes, not typing them. This sounds backwards until you realize that writing by hand engages the brain in a different way (and more deeply) than typing.
You can develop your own "header" system for labeling the cards (dates, classes, ...). You can use different colors of cards for different things. You can carry the most currently relevant cards with you. You can spend a few minutes of otherwise "dead" time reviewing notes.
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From your question it is unclear, whether you are having any specific (academia-related) requirements in addition to the shifted year cycle.
If this is your only issue, you can use any planner which allows you to remove and exchange the calendar sheets. Since the new ones are coming out quite early, it's easy to build the calendar you need...