Bip39 nedir https://rentry.co/p68weyby Although it employs BIP32 process you are able to still import BIP39 seeds into Electrum wallet. Also besides BIp32 There exists BIP44 version which some wallet use to the generation of seeds. For words that have only 3 letters, there is absolutely no 4th letter. One example https://bookmarkspring.com/story15710257/bip39-example-the-single-best-strategy-to-use-for-bip39-word-list-pdf-https-www-youtube-com-channel-ucupxfytj0fb78sq55hu6ocw