Please notice: All lectures are licensed. This means that except where otherwise noted, materials and contents on this site are licensed under a CC BY SA 4.0 license. (https://creativecommons.org/licenses/by-sa/4.0/deed.en ). You are allowed to copy and redistribute, remix, transform, and build upon the material in any medium or format  provided for any purpose, even commercially. You should give appropriate credit, provide a link to the license, and indicate if changes were made. If you remix, transform, or build upon the material, you are supposed to distribute your contributions under the same license as the original.