Lessons 13–14 · 2 lessons · B. Boltayev, A. Azamatov, A. Asqarov, M. Sodiqov, G. Azamatova. Fundamentals of Informatics and Computer Technology, Grade 8. Second edition. “O‘zbekiston milliy ensiklopediyasi” State Scientific Publishing House, Tashkent, 2015