The two orientations used to study knuckle-ball effects. Also

A new take on why a knuckleball is so hard to hit - The Washington Post

Sungchan Hong's research works University of Tsukuba, Tsukuba and other places

Aerodynamics of knuckle ball: Flow-structure interaction problem on a pitched baseball without spin - ScienceDirect

How to Throw Curveball. An Introduction to the Art of the…, by Brent Pourciau

Takeshi ASAI, Prof., Doctor of Engineering, University of Tsukuba, Tsukuba, Faculty of Health and Sport Sciences

PDF) Physics of knuckleballs

What are the advantages and disadvantages of using the knuckleball as a primary pitch in baseball? - Quora

Takeshi ASAI, Prof., Doctor of Engineering, University of Tsukuba, Tsukuba, Faculty of Health and Sport Sciences

John GOFF, Professor of Physics, PhD, Physics

Swing and reverse swing of a cricket ball: laminar separation bubble, secondary vortex and wing-tip-like vortices, Journal of Fluid Mechanics

Computational trajectories for Brazuca and Jabulani balls kicked 30 m/s

How to Throw a Curveball - A Step-by-Step Guide for Pitchers

PDF) A comparison of Jabulani and Brazuca non-spin aerodynamics

Why the knuckleball takes such a knucklehead path

Predicting a Baseball's Path