On the existence of trades of large volumes. - Abdolhossein Hoorfar; Gholamreza B. Khosrovshahi (Ars Comb., 2004)

On the nonexistence of Steiner t-(v, k) trades. - Abdolhossein Hoorfar; Gholamreza B. Khosrovshahi (Ars Comb., 2005)