How to use the Thin Lens Formula to model a thick lens -- PanoHelp.com
Focal Length of a Lens
17. Lenses and Optical Instruments — Modern Lab Experiments documentation
Focal length - Wikipedia
Displacement Method for finding Focal Length of Convex Lens Class 12Optics @Kamaldheeriya Maths easy
MathType - The focal length for a positive converging lens in air is the distance from the lens to the point where the incident light beam is focused. It can be calculated
How to Calculate the Focal Length of a Lens Given Index of Refraction | Physics | Study.com