On the fourth coefficient of univalent functions with bounded boundary rotation

M. Schiffer, O. Tammi
1967 Annales Academiae Scientiarum Fennicae Series A I Mathematica  
Here the points z; (i : I , . . . , -tr[) are the pre-images of the corner points,
doi:10.5186/aasfm.1967.396 fatcat:rrdjdnjvzrgplhtbg5kyly5k5i