SIMPLE SHADOWS        free
ISBN 0-9765286-5-7   

46 page book uses simpleShadows.xls   

and the normal sized book and all the spreadsheets are
in ZIP
form here which also includes three examples of the geometric
method in turboCAD and PDF form

but, for a smart phone, here it is  

includes theory, tables, and templates, 46 pages.

Want more advanced material?
Cubic Shadows here