Tytonidae
Strigidae
Aegothelidae
Podargidae
Batrachostomidae[?]
Steatornithidae
Nyctibiidae
Eurostopodidae[?]
Caprimulgidae
Raphidae[?]
Columbidae
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... The formula reads <math> x=\frac{-b \pm \sqrt {b^2-4ac}}{2a} </math> The term b2 – 4ac is called the discriminant of the quadratic equation, ...