No. 1 from 6 Easy Fugues (Fughettas) collected and
published by Anton Diabelli, Wien 1830:
http://imslp.org/wiki/A_Collection_of_7_Fughettas_(Hand
el%2C_George_Frideric)
The number B 553 in the appendix of the Händel work
list HWV refers to the Baselt catalog:
https://www.pianolibrary.org/composers/handel/works-by-
baselt-catalogue/