1. Birkhoff, G., Bennett, M.K.: The convexity lattice of a poset. Order 2, 223–242 (1985)
2. Freese, R., Ježek, J., Nation, J.B.: Free Lattices, Mathematical Surveys and Monographs, vol. 42. Amer. Math. Soc., Providence, RI (1995)
3. Leclerc, B., Monjardet, B.: Orders “C.A.C.”. Fund. Math. 79, 11–22 (1973)
4. Pouzet, M., Zaguia, N.: N-free extensions of posets. Note on a theorem of P.A. Grillet. Contributions to Discrete Mathematics 1, 80–87 (2006)
5. Rival, I.: Stories about order and the letter ${\sf N}$ (en), Combinatorics and ordered sets (Arcata, Calif., 1985), Contemp. Math., vol. 57, pp. 263–285. Amer. Math. Soc., Providence, RI (1986)