diff --git a/ch04_keys.adoc b/ch04_keys.adoc
index e26b787f..1fce182b 100644
--- a/ch04_keys.adoc
+++ b/ch04_keys.adoc
@@ -944,21 +944,21 @@ Legacy addresses were supplanted by the bech32 family of ((("redemption scripts"
 [[p2sh_collision_attacks]]
 .P2SH Collision Attacks
 ****
-All addresses based on hash functions are theoretically vulnerable to an
+All addresses ((("collision attacks", id="collision")))based on hash functions are theoretically vulnerable to an
 attacker independently finding the same input that produced the hash
 function output (commitment).  In the case of Bitcoin, if they find the
 input the same way the original user did, they'll know the user's private
 key and be able to spend that user's bitcoins.  The chance of an attacker
 independently generating the input for an existing commitment is
 proportional to the strength of the hash algorithm.  For a secure
-160-bit algorithm like HASH160, the probability is 1-in-2^160^.  This is
+160-bit algorithm like HASH160, the probability is 1-in-2^160^.  This ((("preimage attacks")))is
 a _preimage attack_.
 
 An attacker can also try to generate two different inputs (e.g., redeem
 scripts) that produce the same commitment.  For addresses created
 entirely by a single party, the chance of an attacker generating a
 different input for an existing commitment is also about 1-in-2^160^ for
-the HASH160 algorithm.  This is a _second preimage attack_.
+the HASH160 algorithm.  This is((("second preimage attacks"))) a _second preimage attack_.
 
 However, this changes when an attacker is able to influence the original input
 value. For example, an attacker participates in the creation of a
@@ -994,7 +994,7 @@ Bitcoin miners about 32 billion years.
 
 Although we do not believe there is any immediate threat to anyone
 creating new P2SH addresses, we recommend all new wallets use newer
-types of addresses to eliminate address collision attacks((("public key cryptography", "hash functions and", startref="pub-key-hash2")))((("hash functions", "Bitcoin payments and", startref="hash-payment2")))((("payments", "with hash functions", secondary-sortas="hash functions", startref="payment-hash2")))((("P2SH (pay to script hash)", startref="p2sh"))) as a concern.
+types of addresses to eliminate address collision attacks((("public key cryptography", "hash functions and", startref="pub-key-hash2")))((("hash functions", "Bitcoin payments and", startref="hash-payment2")))((("payments", "with hash functions", secondary-sortas="hash functions", startref="payment-hash2")))((("P2SH (pay to script hash)", startref="p2sh")))((("collision attacks", startref="collision"))) as a concern.
 ****
 
 === Bech32 Addresses