Albert Einstein: 5
Hassan coauthored with M. J. Shelley who coauthored with L. P. Kadanoff who coauthored with J. L. Lebowitz who coauthored with P. G. Bergmann who coauthored with A. Einstein

Paul Erdös: 4
Hassan coauthored with H. A. Stone who coauthored with A. Nadim who coauthored with P. Salamon who coauthored with P. Erdös

Ludwig Prandtl: 7
Hassan coauthored with M. J. Shelley who coauthored with L. Truskinovsky who coauthored with A. Mielke who coauthored with K. Kirchgässner who coauthored with H. Görtler who coauthored with K. Wieghardt who coauthored with L. Prandtl

Sir G. I. Taylor: 4
Hassan coauthored with M. J. Shelley who coauthored with Gregory R. Baker who coauthored with P. G. Saffman who coauthored with G. I. Taylor

Clifford Ambrose Truesdell, III: 4
Hassan coauthored with M. J. Shelley who coauthored with L. Truskinovsky who coauthored with R. L. Fosdick who coauthored with C. A. Truesdell

George K. Batchelor: 4
Hassan coauthored with M. J. Shelley who coauthored with A. I. Pesci who coauthored with H. K. Moffatt who coauthored with G. K. Batchelor