This model is posing for a photo session in an artist's studio. She takes her inspiration for the pose from a figure drawing book. It looks like it is Andrew Loomis' Figure Drawing for All It's Worth.
The open page in the first photo looks like page 194, which illustrates distributed weight in a figure.
The nearest page in the second photo looks like a combination of 2 illustrations, page 102 and 106, which illustrate twisting and turning of the figure.
Andrew Loomis was born in 1892. After school he moved to Chicago, and worked in editorial and advertising for most of the top clients at the time including Kellogg's, Coca Cola, Lucky Strike and more. He published Fun With A Pencil
in 1939 and his hugely influential Figure Drawing for All It's Worth
in 1943.
Atelier Edith Glogau - Frauke Lauterbach im Badekostüm
Portrait of Frauke Lauterbach by Lazlo Willinger
German actress Frauke Lauterbach is an actress, known for Fortsetzung folgt (1938), Silhouetten (1936) and Der Mann, der nicht nein sagen kann (1938). - IMDb
Female Proportions, Studies of the nose, lips and chin
Studies of a female torso, studies of a male torso
Males figures
Preissler was a painter and engraver born in 1666 in Nuremberg. He painted mainly portraits and biblical scenes and is now probably best known for his work about life drawing titled, Die durch Theorie erfundene Practic, oder Gründlich-verfasste Reguln (The theory invented by practice, or Multiple-authored Rules). More about him at this post: How to Draw People - Johann Daniel Preissler.
The illustrations here are hand colored and they are for sale on Ebay.
The Art Student's Guide to the Proportions of the Human Form
The Art Student's Guide to the Proportions of the Human Form A republication of Dr. Gottfried Schadow's famous work in which thirty plates demonstrate the proportions of the human form. It is based on the pioneering work of the Greek Sculptor Polycletus. Amazon.com
Followers
The Student's Guide to Expression in Historical Painting
The School of Raphael- Wonderful engravings by Nicholas Dorigny after Raphael's famous designs for the story of early Christianity for the Sistine Chapel, the heads of the figures are used to demonstrate the range of human expressions. Amazon.com
Gerard Audran's The Proportions of the Human Body
In 1683 Gerard Audran produced Les Proportions du Corps Humain which was a careful rendition of the famous statues of antiquity including careful measurements of each. Amazon.com
The Art Student's Guide To External Anatomy
The Art Student's Guide to External Anatomy A republished edition of Dr. Fau's book which was in wide circulation with as many as ten editions in different languages and used by almost every art student in Europe in the mid nineteenth century. The book is in full color. Amazon.com
The Art Student's Guide to the Bones and Muscles of the Human Body
The Art Student's Guide to the Bones and Muscles of the Human Body and Lessons on Foreshortening a republication of the 1892 edition based on Dr. Schadows original 1830 guide for his students. Amazon.com.
The Human Head
A new edition of Louis Bail's method of learning to draw the head. Amazon.com