diff --git a/ch04_keys.adoc b/ch04_keys.adoc
index 6765269a..5b5e0888 100644
--- a/ch04_keys.adoc
+++ b/ch04_keys.adoc
@@ -608,7 +608,7 @@ look at compact encoding and reliable ((("public key cryptography", "hash functi
 [[base58]]
 === Base58Check Encoding
 
-In order to represent long numbers in a compact way,
+In order((("public key cryptography", "base58check encoding", id="pub-key-base58")))((("base58check encoding", id="base58")))((("encoding", "base58check", id="encode-base58"))) to represent long numbers in a compact way,
 using fewer symbols, many computer systems use mixed-alphanumeric
 representations with a base (or radix) higher than 10. For example,
 whereas the traditional decimal system uses 10 numerals, 0 through 9,
@@ -737,7 +737,7 @@ version prefixes and the resulting base58 characters are shown in
 
 Putting together public keys, hash-based commitments, and base58check
 encoding, we can see the illustration of the conversion of a public key
-into a Bitcoin address in <<pubkey_to_address>>.
+into a Bitcoin address((("public key cryptography", "base58check encoding", startref="pub-key-base58")))((("base58check encoding", startref="base58")))((("encoding", "base58check", startref="encode-base58"))) in <<pubkey_to_address>>.
 
 [[pubkey_to_address]]
 .Public key to Bitcoin address: conversion of a public key into a Bitcoin address