diff --git a/blockset-lib/src/secp256k1/nonce.rs b/blockset-lib/src/secp256k1/nonce.rs
index a0188b32..a5c36daf 100644
--- a/blockset-lib/src/secp256k1/nonce.rs
+++ b/blockset-lib/src/secp256k1/nonce.rs
@@ -1,3 +1,5 @@
+// RFC6979 https://www.rfc-editor.org/rfc/rfc6979
+
 use crate::{
     hmac::HmacSha256,
     sha2::be_chunk::BeChunk,