In 1965 the couple travelled to Europe for a holiday where Rica spent some time studying Drummond's plant specimens at the Kew Gardens herbarium in London, which were sent from Western Australia in the mid-19th century. On their return, they retired from farm life and settled in the Perth suburb of Nedlands, where Erickson wrote several more books. She became a member of the Royal Western Australian Historical Society and her writing during this period focussed on the early days of the state's European settlement, and its convict era. She wrote a history of the society called "Forty Years of the Royal Western Australian Historical Society: 1936–1976" which was published in "Early Days". Assisted by a group of volunteers, she compiled the first three volumes of the "Dictionary of Western Australians" in time for Western Australia's sesquicentennial year of 1979.