I don't think they exist. I suggest a solution, the documentation system of our university gives us the possibility to download books and articles for free.
If you need a book or article, send me its title and I will download it for you.
You do not specify what exactly you wish to learn. MATLAB has applications in many fields and therefore there are many books that are invaluable to some, yet rather useless to others.
If you can be more specific I am sure the RG community can conjure up something.
Generally speaking, I have found MATLAB's "help" function very useful. MathWorks also offer a fairly comprehensive website full of tutorials and examples:
You can find a number of free sources for learning Octave which is remarkably like Matlab. There are a few differences but generally Matlab code will run in Octave. Octave users may often use some of the creative freedoms allowed by the opensource nature of Octave so it is possible that some Octave code will not run in Matlab. The differences in the Octave and Matlab parsers is well documented and if you adhere with Matlab syntax while programming in Octave, there should be no problem with portability between the two.