US Airmails Cross Gutter Block question
Do any cross gutter blocks exist for these US airmails?
C7, C8, C9, C10, C12, C16, C17, C18 or C19
I got side tracked and started collecting centerline blocks for the WFs and stumbled across a.nice US 631 Warren Harding cross gutter block, and got to wondering about these airmail issues...and if there were any cross gutter blocks for them?
Thanks in advance,
HT
C7, C8, C9, C10, C12, C16, C17, C18 or C19
I got side tracked and started collecting centerline blocks for the WFs and stumbled across a.nice US 631 Warren Harding cross gutter block, and got to wondering about these airmail issues...and if there were any cross gutter blocks for them?
Thanks in advance,
HT