Here are lists of resources I think are consistent with systematic, explicit, synthetic phonics principles, but please check them out yourself before purchasing. My aim is to help with your search, but inclusion on these lists does not constitute an endorsement.
I’ve included country of origin in brackets (Aus = Australian, UK = British, US = American, Can = Canada, NZ = New Zealand), and highlighted free resources. Please tell me if I’ve left out something good, or you notice something is out of date: email@example.com.
Free books on synthetic phonics for parents and teachers are available at Parker Phonics.
If you want to know how English spelling became so complicated, try the History of English podcast.