diff --git a/ch04_keys.adoc b/ch04_keys.adoc
index 890a0b7c..59036f8e 100644
--- a/ch04_keys.adoc
+++ b/ch04_keys.adoc
@@ -158,7 +158,7 @@ visible universe is estimated to((("public key cryptography", "private keys", "g
 [[elliptic_curve]]
 ==== Elliptic Curve Cryptography Explained
 
-Elliptic curve cryptography (ECC) is a type of asymmetric
+Elliptic curve cryptography (ECC) is((("public key cryptography", "elliptic curve cryptography as", id="pub-key-ecc")))((("elliptic curve cryptography (ECC)", id="ecc"))) a type of asymmetric
 or public key cryptography based on the discrete logarithm problem as
 expressed by addition and multiplication on the points of an elliptic
 curve.
@@ -281,7 +281,7 @@ pass:[+] B pass:[+] C without parentheses and without ambiguity.
 Now that we have defined addition, we can define multiplication in the
 standard way that extends addition. For a point P on the elliptic curve,
 if k is a whole number, then kP = P + P + P + ... + P (k times). Note
-that k is sometimes confusingly called an "exponent" in this case.
+that k is sometimes confusingly called an "exponent" in ((("public key cryptography", "elliptic curve cryptography as", startref="pub-key-ecc")))((("elliptic curve cryptography (ECC)", startref="ecc")))this case.
 
 [[public_key_derivation]]
 ==== Public Keys