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Some additional ressources on tensors I've found useful:

1) A video[0] by Michael Penn exposing this idea of "tensor product of vector spaces." It's close to what is presented in this blog post, but more rigorous/complete.

2) Two videos[1][2] by Frederic Schuller. They are each from of bigger courses (resp. ~Differential Geometry for Physics and Quantum Mechanics), but I think they are self-contained enough to be intelligible. They both present tensors in different settings, so one will have to work a little to unify all this. I like in particular how in [1] he really takes the time to first distinguish between all the different tensor product (of space, of vectors, of operators): the usual notation/terminology can be needlessly confusing for beginners.

[0]: https://www.youtube.com/watch?v=K7f2pCQ3p3U

[1]: https://www.youtube.com/watch?v=OZ1WCyJmjgo

[2]: https://www.youtube.com/watch?v=4l-qzZOZt50