I have very few commentaries on Zachariah besides the old standards: Matthew Henry, Matthew Poole, John Calvin, John Gill, Jameson Faucett & Brown ect. I really should get H. C. Leupold. Recently I happened on The Night Visions of Zechariah by Rev. G. H. Kersten published by the Netherland Reformed Book and Publishing Committee. It is in many ways a fine devotional work. I also recently learned that the Reformed Free Publishing Association has a new release: The Coming of Zions Redeemer by Ronald Hanko