I still need to translate the article into English 😉

Until then, you can check out the original articles:

González-Martínez, Á. et al. (2019) ‘Association between puppy classes and adulthood behavior of the dog’, Journal of Veterinary Behavior. Elsevier Inc, 32, pp. 36–41. doi: 10.1016/j.jveb.2019.04.011.
Kutsumi, A. et al. (2013) ‘Importance of puppy training for future behavior of the dog’, Journal of Veterinary Medical Science, 75(2), pp. 141–149. doi: 10.1292/jvms.12-0008.
Malkani, R. (2019) ‘Resilience in dogs: the importance of early positive socialisation’, Veterinary Ireland Journal, 9(1), pp. 27–29. Available at: http://www.veterinaryirelandjournal.com/images/pdf/small/sa_jan_2019.pdf.
Wormald, D. et al. (2016) ‘Analysis of correlations between early social exposure and reported aggression in the dog’, Journal of Veterinary Behavior: Clinical Applications and Research. Elsevier Inc, 15, pp. 31–36. doi: 10.1016/j.jveb.2016.08.071.