Stanford Engineering Everywhere EE261 - The Fourier Transform and its Applications - VideoLectures - VideoLectures.NET

http://videolectures.net/stanfordee261f07_fourier_transform/

https://see.stanford.edu/materials/lsoftaee261/book-fall-07.pdf

Heat equation on a ring: Fourier Analysis

https://www.math.ubc.ca/~peirce/M257_316_2012_Lecture_12.pdf

https://www.math.vt.edu/people/dlr/m2k_opm_fsolht.pdf

Pauls Online Notes : Differential Equations - Solving the Heat Equation

http://tutorial.math.lamar.edu/Classes/DE/SolvingHeatEquation.aspx