As the study and identification of the different species became more extensive it became clear that identification was not at all easy. Harvey's 1846–51 Phycologia Britannica along with his other publications makes no effort to provide "keys" to help in the identification. In 1931 Newton's Handbook [40] which gave the first key to assist in the identification of algae of the British Isles, in the same year Knight and Park gave a key in their "Manx Algae." [46] Eifion Jones in 1962, wrote a key to the genera of British seaweeds.[47] Others soon followed: Dickinson wrote one entitled British Seaweeds.[48] and Adey and Adey (1973) gave keys to the identification of the Corallinaceae of the British Isles.[49] Abott and Hollenberg, in 1976, published keys to the identification of algae of California.[50]