Recto: The foetus in the womb

Leonardo da Vinci; 11 31/32 in.x 8 21/32 in.; pen and ink over red chalk

Landscape with Cottage and Big Tree

Rembrandt van Rijn; 5 3/64 in.x 1 ft. 19/32 in.; etching and pen on paper

Bust of Pseudo-Seneca

Peter Paul Rubens; 10 7/16 in.x 6 31/32 in.; pen and brown ink over black chalk heightened with white, with brush and gray ink

Satire on Art Criticism

Rembrandt van Rijn; 6 7/64 in.x 7 29/32 in.; pen and brown ink corrected with white

Studies for an Altarpiece with the Virgin Enthroned, Attended by Four Saints (recto)

Polidoro da Caravaggio; 7 61/64 in.x 11 47/64 in.; pen and brown ink, some brush and brown wash

Five grotesque heads, and three heads of men in profile

Leonardo da Vinci; 8 37/64 in.x 6 1/32 in.; pen and ink, over red chalk on paper

The Arcades at the Palais Royal

Louis Léopold Boilly; 1 ft. 2 3/8 in. x 1 ft. 5 63/64 in.; pen and black ink with black and grey wash over traces of graphite on paper

The Alchemist

Pieter Bruegel the Elder; pen

The Alchemist: alchemist and wife

Pieter Bruegel the Elder; pen

The Alchemist: scholar and fool

Pieter Bruegel the Elder; pen

An outcrop of stratified rock

Leonardo da Vinci; 7 9/32 in.x 10 35/64 in.; pen and ink over black chalk on paper

The major organs and vessels

Leonardo da Vinci; 10 15/16 in.x 7 3/4 in.; pen and ink with brown and greenish wash, over black chalk on paper

Nathan Admonishing David

Rembrandt van Rijn; 7 21/64 in.x 10 in.; pen and brown ink, heightened with white gouache on paper

La cruzado libertdora y la revolución del 1870 de Aparicio,

Signed: Manuel Ferrando.

Rocket science and missile engineering.

Mode of access: Internet.