OVL H-Beta 2 inch filter (visual use) - BBC Sky at Night Magazine
Omegon Filters Pro 1.25'' H-Beta filter
Astronomik H-beta Filter | First Light Optics
Useful Filters For Viewing Deep-Sky Objects | Prairie Astronomy Club
Amazon.com : SVBONY SV132 Telescope Filter H-Beta Filter 25nm 1.25 inches Eyepiece Filter for Horsehead Nebula California and Cocoon Nebulae in Dark Skies : Electronics
Astronomik H-Beta 12 nm Visual Filter - 2"
Astro Anarchy: NGC 1499, the "California Nebula", reprocessed