Bip39 mnemonic github https://hectorswwo172.bearsfanteamshop.com/picking-the-right-tools-for-your-bip39-generation-demands Even though it utilizes BIP32 approach it is possible to however import BIP39 seeds into Electrum wallet. Also besides BIp32 You can find BIP44 Variation which some wallet use with the era of seeds. For words that have only 3 letters, there isn't a 4th letter. https://doctorbookmark.com/story20253367/bip39-ian-coleman-not-known-details-about-bip39-generator-https-t-me-bip39-chat