Permanents, Pfaffian orientations, and even directed circuits. Robertson, Neil; Seymour, P.D.; Thomas, Robin — 1999 Annals of Mathematics. Second Series

A new proof of the four-colour theorem. Robertson, Neil; Sanders, Daniel P.; Seymour, Paul; Thomas, Robin — 1996 Electronic Research Announcements of the American Mathematical Society [electronic only]

On a conjecture concerning the Petersen graph. Nelson, Donald; Plummer, Michael D.; Robertson, Neil; Zha, Xiaoya — 2011 The Electronic Journal of Combinatorics [electronic only]