Irfan, Mohamad, et al. “Diagnosis of Asthma Disease and The Levels Using Forward Chaining and Certainty Factor”. Jurnal RESTI (Rekayasa Sistem Dan Teknologi Informasi), vol. 6, no. 5, Oct. 2022, pp. 761-7, https://doi.org/10.29207/resti.v6i5.4123.