These pretty monograms are from a vintage 1954 pattern book of crochet edgings and were originally meant to be filet crochet patterns for trimming sheets. Because filet crochet designs are drawn on a grid they work equally well for cross stitch. Click here for a free pdf with the entire alphabet that you can download to your computer and print out next time you need to add a few letters to a project.
And I'll put a link under the Free Patterns section in the left sidebar so you can find it again easily in the future. If you'd like to see some examples of vintage monograms for inspiration, you'll find a post all about them here.