All of them?
But more specifically Drawing the Head and Hands and Figure Drawing for All Its Worth. If you want them physically (which I super recommend, the experience is much better than having them on PDF or such), there's a bundle on discount right now for $46. It's a ridiculous price considering the books are $40 and $50 respectively if bought separately, or that the bundle is normally $80 (these prices come printed on the book themselves).
Some resources:
I would recommend starting with perspective and doing some of these exercises presented from about the 10 min - 30 min mark to get used to drawing straight lines and working with forms in perspective.
Anatomy's tough because of how much mental work you have to do to turn objects around in the simulated 3D space of your page while remembering all these landmarks, proportions, and factoids about why people look the way they look. The more you work with 3D forms you draw through on your page and get used to doodling boxes / spheres / etc. to pack stuff onto the easier it will be to learn anatomy structures.
As far as how to apply the structure of anatomy? Here's a quick Proko video showing how you progress from primitive 3D forms towards more complicated anatomy.
Beyond that, don't feel like you have to learn it all at once. Don't feel like you have to learn and / or use models or methods exactly as you find them. I'm a pretty big fan of the phrase "if it looks right, it is right." A lot of anatomy study comes down to building a good internal sense of what makes anatomy read correctly and how to correct it when you get that sinking feeling that you made something "off."
There are a lot of granular facts you'll know about the human body, like these rhythms for the leg or these rhythms for the arm. If you can remember the proportions, like mark your elbow at the bottom of the rib cage and put an eye width between your eyes, and you can alternate your curves / outlines / "shape language" you're using to communicate your forms then you'll add a ton of appeal.
Here's the rest of that Proko article the arm picture's taken from, if you're interested.
A recent YouTuber I ran across breaks down a lot of those Loomis books and makes anatomy concepts more accessible. I'd highly recommend giving Tim Mcburnie a watch.
Loomis Box Set - The OG anatomy for artists books
This Russian Book - I can't read this book, but it's got some of the coolest form references I've ever seen for realistic anatomy
Bargue Drawing Course - Good for showing how to block references and build up your details
Gesture Drawing for Animation - This will help you with gestures and the energy of your poses to more clearly convey the action
Morpho Simplified Forms - Helps you break down complicated anatomy
Morpho Anatomy for Artists - More thorough explanation of body parts
This Korean Manga Book - I can't read this book, but it's packed full of gestures and forms for manga art
Some resources:
There are other resources out there to learn color theory, values, and painting techniques but you want to get your drawing down first before you worry about rendering out a manga.
Work on your:
There's hatching, color, values, painting, and other rendering related ideas to consider but for purely drawing related to human figures that should cover quite a bit.
The value in learning any single model for anatomy proportions is so you can understand relative sizes in any head proportions. If you're trying to learn a single, definitive set of proportions then you will never find one. When you do character design work you have to establish how many heads your character model will be built on and transfer your concept art into a reproducible model.
That's what you're doing when you draw from life. You're taking the body landmarks learned from a 6.5 heads, a 7, a 7.5, an 8 head model or whatever else you know them from and mapping them onto your figure. Loomis talks about this specifically in his Figure Drawing For All It's Worth because he knew advertisers of the time wanted idealized bodies so he cautioned artists that 8 heads were not realistic for the average person. He specifically wrote that artists who used his 8 headed model for advertising should interpret their real life figure drawing model through that model by changing them in certain ways. He talks about how you'll get more work drawing portraits for families if you straighten the jaw line of women because they'll have more appeal, that you should stretch proportions so you don't draw people as they are. I believe he called 6.5 head proportions "dumpy" and unappealing, which is why advertisers and customers wanted something like the 8 head.
The only reason why we use a particular head measurement is to determine height relative to something other than actual height on a canvas. If someone's 3-4 heads they'll be seen more childishly, 5-6 heads will come off as more teenage years, and anything above 8 heads tall will be seen as fitting for godlike characters. Regardless of what model you use you can follow the same rules learned from the 8 headed model and it will come out looking consistently human like.
That means no matter what size you draw the head if you put the bottom of the pelvis at the halfway mark between the bottom of the head and the bottom of the feet (making it the body's half way mark) you'll come away with a pretty squared off, normal looking body. If you do something like a 6 headed character where two heads are devoted to the upper body and the remaining 3 heads go to the legs below the pelvis then it'll still look realistic enough, but you'll have those longer, heroic leg lengths in a smaller model design.
Elbows should still break at around the base of the ribcage, knees should sit on the halfway mark between bottom of pelvis on the bottom of the feet (so the knees are in the bottom most of the upper half of the leg lengths), etch. Those rules transcend whatever model you learn from and that's the kind of thing you should be looking for in any model you study for generalized human anatomy / figure drawing.
If you want something comprehensive, then look at Proko's Figure Drawing and Human Anatomy playlists. I'd also recommend picking up Figure Drawing For All It's Worth and Drawing the Head and Hands by Loomis. Those Loomis plates for head and face, hand, and body proportions and placements are amazingly clear, concise, and informative.
Both of those are from Figure Drawing For All It's Worth.
There are a lot of differences between male and female bodies. Some notable points to remember: Male shoulders and rib cages will be wider, they'll have thinner pelvises, and their trochanters come out at a less severe angle from the body. In profile view the pelvis on a female tilts up in the back at a greater degree than that of a male.
Learn how to construct the things you want to draw, then you can draw anything you're inspired to.
For figure drawing, I'll recommend Andrew Loomis, Proko, and Aaron Blaise over at CreatureArtTeacher.
I can recommend other resources if you're after other things like landscapes, realistic animals, fantasy animals, cartoons, etc.
One thing I'll note is the more you study realistic figure drawing, the more you can draw believable figures. Every animator, cartoonist, comic artist, etc. that I've read on that topic has said the same thing, that the more you study and learn your realistic human anatomy the easier it is to push, pull, bend, break, and make the rules work for you. All that scary looking, super dense anatomy knowledge that seems so rigid when you're starting to learn becomes immensely freeing when you don't have to think about what to put where to get a believable character design.
I don't think you're creating enough of a separation between obliques and the pelvis, which is leading your torso to look long to you. That belly button should be much higher, right in the center or above center of the obliques, but you need to create more space below the obliques for the iliac crests of your pelvis.
See how much more space there is between the bottom of the obliques sitting on the illiac crests and the belly button above? See how much of a clear plane change there is between obliques and the pelvis?
Realistically, I don't think your torso's crazy long, I just think you need to properly segment it out.
I'd recommend you draw a copy of your figure directly to the right of what you currently have and keep the outline and size the same. Then go over the new outline and put in markers according to the Loomis reference I gave you. I think it'll help you understand how to properly segment the torso.
The sternum should end right below the pectoral muscles, there shouldn't be as much space as you've given.
Add more angle to the ribs below your sternum, they actually come down more so than out horizontally the way you've drawn them.
The pectoral muscles attach at the clavicles, sternum, and across the ribs so you want to bracket the pectoral muscles with the clavicles and I don't see that clear collar bone distinction. You've actually drawn the pectorals in a fair place; if anything you could lower them but probably want to keep them where they are.
The elbows sit at the bottom of the rib cage, which means you've drawn your elbows way, way too low. You've also drawn the deltoids too low. Deltoid muscles make a point on the outside of the arm on basically the same line as the pectoral muscle lower boundary. Then you mark about halfway (favoring the lower half) down the pectoral muscle and that's where your deltoid climbs up from the outside of the arm across the top of the bicep to merge back into the torso.
Wrists break right at the bottom of the pelvis / crotch with fingers extending at a neutral hang down to about the mid thighs, though never to the knees.
For more references, including that image I linked, I'd recommend learning the 8 headed Loomis model for studying human anatomy.
It's from Loomis' Head and Hands, which is usually found in a box set offered with Figure Drawing For All It's Worth.