Bondoc, O., and J. Isubol. “Reasons for Culling in Relation to Longevity and Lifetime Efficiency of Landrace and Large White Sows in a Nucleus Breeding Farm in the Philippines”. Tropical Animal Science Journal, vol. 45, no. 1, Feb. 2022, pp. 30-36, https://doi.org/10.5398/tasj.2022.45.1.30.