Ṣẹda ẹya ti o nira diẹ sii ti gbolohun yii M.Stroppel 1995'' Awọn ọkọ ofurufu Compact Projective ', W. de Gruyter 87.7.
Dajudaju, ẹya ti o nira diẹ sii ti gbolohun naa ni "M.Stroppel 1995'' Compact Projective Planes ', W. de Gruyter Orí 8 ati diẹ sii laipe ni H. Salzmann 2014'' Awọn ọkọ ofurufu Compact, julọ 8 -dimensional. "