A historical document is not made to order. Or rather if it is you should re-consider your acquisition. If you excessively organize your collecting, you will yourself passing by other, significant pieces that would be equally interesting. Example: looking for a letter of Henry Clay relating to his work in the Senate? You might also find interesting this document, which is a fascinating glimpse into the Senate as it stood in 1850, with signatures of Clay and many of his contemporaries.