https://www.abebooks.com/9780704332188/Lotte-Berk-Method-Exercise-0704332183/plp
Lotte Berk: Method of Exercise - Lotte Berk: 9780704332188 - AbeBooks
1978: by Lotte Berk and Jean Prince- Jean Prince attended Lotte's classes and she describes her experiences in detail.
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https://store.lotte-berk.com/product/selection-03-upper-arms-bingo-wings-and-shoulders/
Selection 03 – Upper arms, bingo wings and shoulders – Lotte Berk store
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