AmazingRibs.com features a step-by-step guide to building a wood-fired oven as a free, downloadable PDF. MyOutdoorPlans.com also contains detailed instructions for building a wood-fired oven.
The AmazingRibs.com guide to building a wood-fired oven features color diagrams, a list of required supplies, detailed steps, advice about mixing and testing clay, and information on building an oven door. The website also offers advice and articles about barbecuing and grilling, designing outdoor kitchens and reviews of outdoor oven models.
Hosted by a civil construction engineer, MyOutdoorPlans.com contains a DIY post for building a wood-fired oven from scratch over the course of two weekends. This tutorial is not in PDF format, but the website is printer-friendly.