Bosch spark plug interchange charts are available on Angelfire.com and ProGreenGrass.com, as of 2016. Additional sources for spark plug cross reference charts and guides include E3SparkPlugs.com, NightRider.com and Sparkplug-CrossReference.com.
Angelfire.com provides a chart that cross-references spark plug types for a number of manufacturers, including NGK, AC Delco, Autolite and Bosch. Mower Parts Zone features a chart that cross-references plugs from Denso, Champion, AC Delco and Bosch.
Sparkplug-CrossReference.com features an online converter that cross-references nearly all spark plug brands and types. The website also provides a quick search alternative that allows users to search plug references by part number. NightRider.com provides charts that references plug manufacturers by engine type.