About the size of Google Scholar: playing the numbers

(page 2). The recent work of Khabsa and Giles (2014) has estimated the number of circulating documents written in English in the academic Web on 114 million (and also that of those, GS has around 99.8 million), employing a procedure based on the use of the Lincolm-Petersen (capture-recapture) method, from the citations to a sample of articles written in English, included both in GS and MAS.