以下のページを参考にした。

[nexus7]
https://gadgetrip.jp/2018/03/install_oreo_to_nexus7_2013/

[nexus5]
https://dyoko.com/wp2016/?p=1354
https://nabe.adiary.jp/0613
https://wspri.dip.jp/?p=383
https://forum.xda-developers.com/google-nexus-5/development/rom-pixel-experience-9-0-t3975925
https://sites.google.com/site/radikaiwarehouse/setup_nexus5_pie
https://plaza.rakuten.co.jp/sorriman/diary/202006100000/
http://tekitoukatta.blog.jp/archives/19448025.html
https://sourceforge.net/projects/hammerhead-twrp/
https://sourceforge.net/projects/hammerhead-twrp/files/twrp-3.3.1-HH-hammerhead.img/download
https://www.ish.org/blog/?p=1973