If Bertha's middle initial stands for Elizabeth, this might be their marriage. I found it on Ancestry.

Missouri Marriage Records, 1805-2002
Name: W L George of Howard, Jasper, Missouri, who is over 21
Marriage Date: 17 Mar 1898
Marriage Location: Joplin, Jasper, Missouri
Marriage County: Jasper
Spouse Name: Lizzie Casey of Howard, Jasper, Missouri, who is over 18