* Francis Borceux: "Handbook of Categorical Algebra 3: Categories of Sheaves", Volume 52 of the Encyclopedia of Mathematics and its Applications, Cambridge University Press, Cambridge, 1994.
;Reference works for experts, less suitable for first introduction:* Francis Borceux (1994) "Handbook of Categorical Algebra 3: Categories of Sheaves", Volume 52 of the "Encyclopedia of Mathematics and its Applications".