CMB references
This is good: https://en.wikipedia.org/wiki/Cosmic_microwave_background (the refs, esp to Wayne Hu's work, are good)
http://www.astro.yale.edu/astro120/astro120-2016-class22.pdf
https://www.ast.cam.ac.uk/~pettini/Intro%20Cosmology/Lecture09.pdf
Recombination was not an instantaneous process but proceeded relatively quickly nevertheless, with the fractional ionisation decreasing from X = 0.9 to X = 0.1 over a time interval ∆t ∼ 70 000 yr. With the number density of free electrons dropping rapidly, the time when photons and baryons decoupled follows soon, once the rate for Thomson scattering falls below the expansion rate H. Section 9.3, Photon Decoupling, pg 6
DETERMINING COSMOLOGICAL PARAMETERS FROM ANISOTROPIES IN THE CMB
https://ned.ipac.caltech.edu/level5/Sept02/Reid/Reid5.html
This is quite good: http://www.ita.uni-heidelberg.de/research/bartelmann/files/VLLohmen.pdf
Physics of the cosmic microwave background anisotropy https://arxiv.org/pdf/1501.04288.pdf
Wayne Hu's writings: CMB, power spectrum, BAO, etc
https://www.reddit.com/r/AskPhysics/comments/8i79wf/why_do_we_believe_there_is_dark_matter/
http://background.uchicago.edu/~whu/intermediate/intermediate.html
great graphic: http://background.uchicago.edu/~whu/intermediate/driving2.html
Also, his BAO section: http://background.uchicago.edu/~whu/power/bao.html
Lecture notes from introductory cosmology course: e.g., cosmic geometry etc http://background.uchicago.edu/~whu/Courses/ast243_18.html
Halverson - Measuring the CMB Angular Power Spectrum with DASI.pdf
The simplicity of CMB physics - due to linearity - is mirrored in analysis by the apparent Gaussianity of both the signal and many sources of noise... The Gaussianity of the CMB is not shared by other cosmological systems since gravitational non-linearities turn an initially Gaussian distribution into a non-Gaussian one. http://background.uchicago.edu/~whu/araa/node32.html
most of the secondary anisotropies are not linear in nature and hence produce non-Gaussian signatures. Non-Gaussianity in the lensing and SZ signals will be important for their isolation. The same is true for contaminants such as galactic and extragalactic foregrounds. Finally the lack of an initial non-Gaussianity in the fluctuations is a testable prediction of the simplest inflationary models [Guth & Pi, 1985,Bardeen et al, 1983]. Consequently, non-Gaussianity in the CMB is currently a very active field of research. http://background.uchicago.edu/~whu/araa/node31.html
Physics of the cosmic microwave background anisotropy, by Martin Bucher https://arxiv.org/abs/1501.04288
New physics from the Cosmic Microwave Background, by Douglas Scott https://arxiv.org/abs/astro-ph/9911325
The Cosmic Microwave Background: The history of its experimental investigation and its significance for cosmology | https://arxiv.org/abs/1506.01907 | arXiv:1506.01907 [astro-ph.CO] | Ruth Durrer
A CMB Polarization Primer | https://arxiv.org/abs/astro-ph.CO/9706147 | arXiv:astro-ph.CO/9706147 | Wayne Hu and Martin White
The big-bang theory: construction, evolution and status | https://arxiv.org/abs/1606.06112 | arXiv:1606.06112 [astro-ph.CO] | Jean-Philippe Uzan
General Relativity and Cosmology: Unsolved Questions and Future Directions | https://arxiv.org/abs/1609.09781 | arXiv:1609.09781 [gr-qc] | Ivan Debono and George F. Smoot