How to Use Oscilloscopes and Other Test Equipment by R.A. Penfold 1st Edit 1989

Power Supply Projects R. A. Penfold Bernard Babani BP76 Hobby Electronics

Boost Your Child's Immune System: A Program and Recipes for R... by Burney, Lucy

Circuit Source: Bk. 2 (BP S.) - Penfold, R. A. 1990s Paperback *C

Getting the Most from Your Multimeter (BP), R.A. Penfold, Used(Paperback, 1988)

A Beginner’s Guide to TTL Digital ICs. R.A. Penfold. 1993. Logic Circuits Book

Getting the Most from Your Laptop By R. A. Penfold

Easy PC Upgrading (BP) By R. A. Penfold