--- a/final_pre/reference.bib	Tue Feb 19 15:28:07 2019 +0900
+++ b/final_pre/reference.bib	Tue Feb 19 21:49:55 2019 +0900
@@ -43,6 +43,21 @@
 	Read = {0},
 	Title = {Paxos Made Simple},
 	Year = {2001}}
+	
+@manual{bitcoin,
+      title  = "Bitcoin: A Peer-to-Peer Electronic Cash System",
+      author = "Satoshi Nakamoto",
+      url    = "https://bitcoin.org/bitcoin.pdf",
+      year   = "Accessed: 2019/2/15"
+    }
+    
+@manual{ethereum,
+      title  = "Ethereum Homestead Documentation",
+      author = "",
+      url    = "http://www.ethdocs.org/en/latest/",
+      year   = "Accessed: 2019/2/17"
+    }
+   
 
 @comment{BibDesk Static Groups{
 <?xml version="1.0" encoding="UTF-8"?>