Changes

:[https://www.amazon.co.uk/gp/product/17829455981292120223/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=17829455981292120223&linkCode=as2&tag=nrjc-21&linkId=ad276ad49df77ab4b40ab4fd0fe10152 068ecf40278c32406a7f1c6e66751417 ''Period (of a wave), page 49, GCSE Physics, Pearson Edexcel '']:[https://www.amazon.co.uk/gp/product/1782945733/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945733&linkCode=as2&tag=nrjc-21&linkId=2a2dbec9db6bf5766c0458d908fa0a52 ''Period (wave), page 32, GCSE Physics; The Revision Guide, CGP, Edexcel '']:[https://www.amazon.co.uk/gp/product/1782948163/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782948163&linkCode=as2&tag=nrjc-21&linkId=0fdbfd5dd397d6e24a9dfb250f08587f ''Period (waves), page 91, GCSE Physics, CGP, Edexcel '']:[https://www.amazon.co.uk/gp/product/1782945741/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945741&linkCode=as2&tag=nrjc-21&linkId=30da4f2178da182547b62a7329d13b57 ''Periods (waves), page 164, GCSE Combined Science; The Revision Guide, CGP, Edexcel '']:[https://www.amazon.co.uk/gp/product/1782945725/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945725&linkCode=as2&tag=nrjc-21&linkId=694be7494de75af3349537d34e13f7f0 ''Periods, page 18, GCSE Chemistry; The Revision Guide, CGP, Edexcel ''] ====OCR====:[https://www.amazon.co.uk/gp/product/1782945687/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945687&linkCode=as2&tag=nrjc-21&linkId=9a598e52189317a20311d7a632747bc9 ''Period (of a wave), page 59, Gateway GCSE Physics; The Revision Guide, CGP, OCR '']:[https://www.amazon.co.uk/gp/product/0198359837/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359837&linkCode=as2&tag=nrjc-21&linkId=3c4229e8b023b2b60768e7ea2307cc6f ''Period (waves), pages 142-143, Gateway GCSE Physics, Oxford, OCR '']:[https://www.amazon.co.uk/gp/product/1782945695/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945695&linkCode=as2&tag=nrjc-21&linkId=ceafcc80bcad6b6754ee97a0c7ceea53 ''Periods (in the periodic table), page 10787, Gateway GCSE Combined Science; The Revision Guide, CGP, AQA OCR '']:[https://www.amazon.co.uk/gp/product/17829455711782945695/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=17829455711782945695&linkCode=as2&tag=nrjc-21&linkId=9e29fad914244909903e5e93f8a01d205 ceafcc80bcad6b6754ee97a0c7ceea53 ''Periods (of the periodic tablea wave), page 22186, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR '']:[https://www.amazon.co.uk/gp/product/1782945679/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945679&linkCode=as2&tag=nrjc-21&linkId=a2db42f7b4bdf10cafaafa3bb9120940 ''Periods, page 16, Gateway GCSE Chemistry; The Revision Guide, CGP, AQA OCR '']