Insulin signaling and limb-patterning: candidate pathways for the origin and evolutionary diversification of beetle 'horns' | Heredity
How the rhinoceros beetle got its horn
Rhinoceros beetles: one of the strongest insects with horned heads | One Earth
Notch signaling patterns head horn shape in the bull-headed dung beetle Onthophagus taurus | SpringerLink
Scientists turned dung beetle horns into 'cyclops' eyes - Futurity
On the origin and evolutionary diversification of beetle horns | PNAS
Minotaur beetle, Typhoeus typhoeus, with two large horns protuding forward from the head and one horn pointing upwards, segmented body is covered by glossy black wings, side view Stock Photo - Alamy
Eastern Hercules Beetle, No 1 | Mississippi State University Extension Service
Super Bug! World's Strongest Insect Revealed | Live Science
Beetle | San Diego Zoo Animals & Plants
Rhinoceros beetle - Elegant Entomology
British beetle guide: where to see and how to identify | Countryfile.com