It's interesting that this isn't straightforward to answer.
I would note, discussions of free will come down primarily to definitions, so what tradition or perspective someone comes from is key to not just ending up talking at cross purposes.
And, a lot of the key work is in books. Not just modern ones: Boethius Descartes Hobbes Spinoza Locke and Kant are all important background - I find Aristotle's thoughts on supervenient souls strikingly contemprarily relevant also. Contrasting assumptions have also often been particularly clearly revealed in debates, also.
You might consider picking up The Philosophy of Free Will: Essential Readings From the Contemporary Debates, which has readings from 1929 onwards. Or Four Views on Free Will, which summarises the main four 'camps' in the modern debate. Or Essays on Free Will and Moral Responsibility. All available on Z Library. Or you might go through the resources at The Information Philosopher: Free Will.
I am going to take this question as requesting, short-form work that provides touch-stones in the development and articulation of the modern discussion of free will. Criteria for notability I take to be, being widely quoted.
Of liberty and Necessity, in A Treatise of Human Nature (2.3.1–2), by Hume. An early and cornerstone articulation compatibilist thought:
"I hope, therefore, to make it appear that all men have ever agreed in
the doctrine both of necessity and of liberty, according to any
reasonable sense, which can be put on these terms; and that the whole
controversy, has hitherto turned merely upon words."
Schopenhaur's 1839 essay On The Freedom Of The Will. From which:
"In a word: Man does at all times only what he wills, and yet he does
this necessarily. But this is due to the fact he already is what he
wills."
The chapter Free Will in GE Moore's 'Ethics':
"Those who hold that we have Free Will, think themselves bound to
maintain that acts of will sometimes have no cause; and those who hold
that everything is caused think that this proves completely that we
have not Free Will."
'What life means to Einstein'is a 1929 interview with Einstein published in US magazine The Saturday Evening Post, which PDFs are available of online. In it he gave probably his clearest statement about his views on free will:
"I am a determinist. As such, I do not believe in free will. The Jews
believe in free will. They believe that man shapes his own life. I
reject that doctrine philosophically. In that respect I am not a Jew…
Practically, I am nevertheless, compelled to act as if freedom of the
will existed. If I wish to live in a civilized community, I must act
as if man is a responsible being.”
'Freedom and Resentment' by Strawson:
"If someone treads on my hand accidentally, while trying to help me,
the pain may be no less acute than if he treads on it in contemptuous
disregard of my existence or with a malevolent wish to injure me. But
I shall generally feel in the second case a kind and degree of
resentment that I shall not feel in the first. If someone's actions
help me to some benefit I desire, then I am benefited in any case; but
if he intended them so to benefit me because of his general goodwill
towards me, I shall reasonably feel a gratitude which I should not
feel at all if the benefit was an accidental consequence unintended or
even regretted by him, of some plan of action with a different aim."
In Defence of Free Will, C.A. Campbell:
"I am not myself...disposed to rest any part of the case against
universal determinism upon these recent dramatic developments of
physical science."
His critique of Logical Positivist Schlick also: Is Free Will A Pseudo-Problem?
Freedom and Necessity, A.J. Ayer:
"It seems that if we are to retain this idea of moral responsibility,
we must either show that men can be held responsible for actions which
they do not do freely, or else find some way of reconciling
determinism with the freedom of the will."
'Elbow Room: The Varieties of Free Will Worth Wanting' by Dennett is 216 pages, based on a short lecture series:
"There's no sense wringing our hands because we can't undo the past,
and can't prevent an event that actually happens, and can't create
ourselves ex nihilo, and can't choose both alternatives at a decision
point, and can't be perfect"
I would argue free will has become a special category in Western Philosophy because it arose from theodocies grappling with The Problem Of Evil, and an implicit assumption tends to remains that moral responsibility means a judgement on someone's inner essence, separated from causes and conditions. As discussed here: Does philosophy have a dark side?
I'd also say reifying Free Will into absolute terms is misleading, we should focus on more or less free in our choices, and that the direction of being more free we already have a name for, and it is wisdom: If Free Will Is Proven Illusory, Is There a Case for Suppressing the Finding?
