diff --git a/aescbctest.c b/aescbctest.c
index bf7e01e..5a732b4 100644
--- a/aescbctest.c
+++ b/aescbctest.c
@@ -22,6 +22,8 @@
 #include <orca.h>
 #include "aes.h"
 
+/* Example vectors from NIST SP 800-38A */
+
 unsigned char iv[16] = {
     0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,
     0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f
diff --git a/aesctrtest.c b/aesctrtest.c
index c569adf..77e869e 100644
--- a/aesctrtest.c
+++ b/aesctrtest.c
@@ -24,6 +24,8 @@
 #include <orca.h>
 #include "aes.h"
 
+/* Example vectors from NIST SP 800-38A */
+
 unsigned char initial_counter[16] = {
     0xf0,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,
     0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfe,0xff
diff --git a/aestest.c b/aestest.c
index 68b72a4..2187f6b 100644
--- a/aestest.c
+++ b/aestest.c
@@ -23,6 +23,8 @@
 
 #include "aes.h"
 
+/* Example vectors from FIPS 197, Advanced Encryption Standard (AES) */
+
 void print_hexbytes(char *prefix, unsigned char *data, unsigned int n) {
     int i;