Lucy Mack Smith
Young Joseph's leg operation, accounts of persecution the Smiths suffered from people trying to obtain the golden plates and details about the great sense of loss the family felt when the oldest son, Alvin, died all came from the record kept by Lucy Mack Smith. According to Sharalyn Howcroft, assistant archivist for the Joseph Smith Papers project, Lucy's record provides details that Joseph's own history did not.
Ref. Source 8
Lucy Mack Smith (Hover)