Look for "Freehand Drawing: A Manual for Teachers and Students" by Anson K. Cross (public domain) or works by Rex Vicat Cole – "The Artistic Anatomy of Trees" (free).
: A massive repository for out-of-print and public domain books. It hosts complete instructional guides like Art Fundamentals: Theory and Practice Look for "Freehand Drawing: A Manual for Teachers
To create compelling work, you need to master these five areas: Prefeitura de São Paulo Art Fundamentals: Theory & Practice PDF - Scribd Look for "Freehand Drawing: A Manual for Teachers