Bip39 mnemonic github http://www.mediafire.com/file/uilrjfajg2ami24/pdf-14673-57158.pdf Mycelium - A cell wallet that supports BIP39 seed phrases and has State-of-the-art functions for electrical power customers. For words that have only 3 letters, there isn't a 4th letter. One example is With all the word “insert”, there are no more letters afterwards and therefore https://squareblogs.net/edelinepge/using-python-to-produce-a-bip39-mnemonic-a-developers-point-of-view