1. Over de combinatorische opgave van Steiner;Barrau;Kon. Akad. Wetensch. Amst. Verlag Wis-en Natuurk. Afd.,1908
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3. On cyclic Steiner quadruple systems;Cho;Are Combinatoria,1980
4. C.J. Cho, private communication.
5. A recursive construction for infinite familes of cyclic SQS;Colbourn;Are Combinatoria,1980