On a New Kind of Collection of Subsets Noted by Î´â€“field and Some Concepts Defined on Î´â€“field
Mağallaẗ Ibn al-haytam li-l-ʻulūm al-ṣirfaẗ wa-al-taṭbīqiyyaẗ/Ibn al-Haitham journal for pure and ap‪plied sciences