Palms and cycads

American fossil cycads

G. R. Wieland

1906

The living cycads

Charles Joseph Chamberlain

1919

Cycads of the world

David L. Jones

1993

Some characters of Xylem tissue in Cycads and The bar of Sanio and primordial pit in the Gymnosperms

Harold Boyd Sifton

1900

The Cycads

Loran M. Whitelock

2002

Recherches sur l'organisation des tiges des Cycadées

Adolphe Brongniart

1829

Cycads of South Africa

Cynthia Giddy

1974

Cycads of Africa

Douglas Goode

1989