BibliOdyssey has a few illustrious Dutch picture book cover illustrations up from The Memory of the Netherlands’ ‘Picture Books from 1810 to 1950‘ website – which features 650 antique children’s books free to view in full and download. Going to waste a lot of time if I start trawling through those archives with illustrations as gorgeous as the ones PK linked; favorites so far:

'Feest in het Bosch', story by Jac. van der Klei, illustrated by D. Viel, 1927 *click thru to big*

Alle eendjes by Uitgever 1930 *click thru to big*

'Uit Huis en Hof' by Konrad Mullerfurer, 1921 *click thru to big*

'Van twee visschertjes een vertelling voor klein en groot met rijmpjes en knipsels door J.E.' by Enderlein, J. 1913 *click thru to big*

'De Gouden Haan' by Marietje Witteveen, 1940 *click thru to big*

'A dat is Aafje - door Bas van der Veer' by Bas van der Veer and Freddie Langeler *click thru to big*

'De Reis Naar de Maan' by PJ Andriessen, 1876 *click thru to big*

'De Wilgen by Adama van Scheltema', illustrated by Rie Cramer, 1918 *click thru to big*

'Waarom de slak zijn huisje altijd met zich meedraagt een verhaal van Vadertje Brombeer' by Brombeer, Vadertje 1946 *click thru to big*

'Het Theesalet van Pieteloet' by Agatha, 1860 *click thru to big*

'Landelijke Tafereelen' published by J Scholz, 1860s *click thru to big*

'Het ABC voor Holland's Kleintjes met 156 Plaatjes' by Daan Hoeksema, 1923 *click thru to big*

'Het Prentenboek der Sporten' by Yvonne, 1912 *click thru to big*

'Pierrot', text by J. Schenkman, illustrated by Louis Raemaekers, 1907 *click thru to big*
“Old children’s books are moving, intriguing, amusing and inspiring. They have value not only for the individual reader, but also for our society as a whole. Each successive Dutch generation grew up with its own specific children’s books, and each generation unconsciously adopted such moral standards and values as they contained. Children’s books serve as indispensable witnesses of an ever changing society
Within the framework of youth literature, picture books occupy a special place. In picture books, the images are just as important as the texts. They are by no means intended exclusively for young children. Old picture books reflect the views people held about good and evil, poor and rich; about education, with examples of dutiful and bad behaviour; about love for one’s own country and about people from foreign countries. They illustrate a changing world of new inventions and modes of transport, of living and fashion, of daily life in towns and villages. There is both humour and moralism to be found in children’s books; they play with the relationship between reality and fantasy.
A total of six hundred and fifty Dutch picture books, dating to the period 1810–1950, are brought together in this collection, which runs the gamut from Robinson Crusoe to Tielse Flipje (a cartoon mascot on ‘De Betuwe’ jam pot labels) and from old nursery rhymes to fairy tales from the Brothers Grimm: there is something for everyone in the collection.“