[1] 非公式 SSTP/1.x プロトコル仕様書 http://www2.wbs.ne.jp/~dskoba/database/sstp.html
[3] 伺か - SSTPプロトコル (2007-09-14 12:30:05 +09:00 版) http://usada.sakura.vg/contents/sstp.html
[2] NANIKA(en) - SSTP protocol (2001-09-08 00:49:51 +09:00 版) http://homepage1.nifty.com/znc/redo/sstp.html

[4] [MS-SSTP]: Secure Socket Tunneling Protocol (SSTP) (2017-09-06 21:22:24 +09:00) https://webcache.googleusercontent.com/search?q=cache:Jkzip1J7k6oJ:https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-SSTP/%5BMS-SSTP%5D.pdf