diff --git a/ch04.asciidoc b/ch04.asciidoc
index 8dd1987f..65bce68d 100644
--- a/ch04.asciidoc
+++ b/ch04.asciidoc
@@ -566,7 +566,7 @@ image::images/msbt_0408.png["non-deterministic wallet"]
 
 ((("deterministic wallets","mnemonic code words")))((("mnemonic code words")))((("seeded wallets","mnemonic code words")))Mnemonic codes are English word sequences that represent (encode) a random number used as a seed to derive a deterministic wallet. The sequence of words is sufficient to re-create the seed and from there re-create the wallet and all the derived keys. A wallet application that implements deterministic wallets with mnemonic code will show the user a sequence of 12 to 24 words when first creating a wallet. That sequence of words is the wallet backup and can be used to recover and re-create all the keys in the same or any compatible wallet application. Mnemonic code words make it easier for users to back up wallets because they are easy to read and correctly transcribe, as compared to a random sequence of numbers. 
 
-Mnemonic codes are defined in((("BIP0039"))) Bitcoin Improvement Proposal 39 (see pass:[<xref linkend="bip0039" xrefstyle="select: labelnumber"/>] pass:[<xref linkend="bip0039" xrefstyle="chap-num-title"/>] <<bip0039>>), currently in Draft status. Note that BIP0039 is a draft proposal and not a standard. Specifically, there is a different standard, with a different set of words, used by the((("Electrum wallet")))((("mnemonic code words","Electrum wallet and"))) Electrum wallet and predating BIP0039. BIP0039 is used by the((("mnemonic code words","Trezor wallet and")))((("Trezor wallet"))) Trezor wallet and a few other wallets but is incompatible with Electrum's implementation. 
+Mnemonic codes are defined in((("BIP0039"))) Bitcoin Improvement Proposal 39 (see <<bip0039>>), currently in Draft status. Note that BIP0039 is a draft proposal and not a standard. Specifically, there is a different standard, with a different set of words, used by the((("Electrum wallet")))((("mnemonic code words","Electrum wallet and"))) Electrum wallet and predating BIP0039. BIP0039 is used by the((("mnemonic code words","Trezor wallet and")))((("Trezor wallet"))) Trezor wallet and a few other wallets but is incompatible with Electrum's implementation. 
     
 BIP0039 defines the creation of a mnemonic code and seed as a follows: