Raising Cane - The Unexpected Martial Art by Octavio Ramos
A serious book for a serious subject. We're all going to get old you know (if we're lucky.)
ENasco.com farm/ranch supply sells cheap, octagonal, hardwood canes used for working with livestock. Take a few inches off the hook, practice the basic forms and katas in Mr. Ramos' book and you'll have a great defensive tool for times when you're faced with dangerous urban livestock.
Cattleman's cane 7/8 inch diameter
Bullworker's cane 1 1/8 inch diameter
The 7/8 inch diameter cane seems a bit flimsy to me, but anything 1 inch and thicker might be barred from some venues (it hasn't happened to me yet - but I'm old and walk with a practiced limp.)