diff --git a/library/x509_crt.c b/library/x509_crt.c
index 50f92e6..c5f7f70 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1,5 +1,5 @@
 /*
- *  X.509 certificate and private key decoding
+ *  X.509 certificate parsing and verification
  *
  *  Copyright (C) 2006-2014, Brainspark B.V.
  *
@@ -25,10 +25,9 @@
 /*
  *  The ITU-T X.509 standard defines a certificate format for PKI.
  *
- *  http://www.ietf.org/rfc/rfc3279.txt
- *  http://www.ietf.org/rfc/rfc3280.txt
- *
- *  ftp://ftp.rsasecurity.com/pub/pkcs/ascii/pkcs-1v2.asc
+ *  http://www.ietf.org/rfc/rfc5280.txt (Certificates and CRLs)
+ *  http://www.ietf.org/rfc/rfc3279.txt (Alg IDs for CRLs)
+ *  http://www.ietf.org/rfc/rfc2986.txt (CSRs, aka PKCS#10)
  *
  *  http://www.itu.int/ITU-T/studygroups/com17/languages/X.680-0207.pdf
  *  http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf