The idea of a classification of accounting services originated with John R. Wildman who was the senior technical partner for the firm of Haskins & Sells during the 1920's and under whose direction the writer was employed fifty years ago. Haskins & Sells has continued the use of classification of accountancy services, originally adopted in 1925, to this date modified as required by the enactment of the Federal Securities Acts.
Johns, Ralph Stanley
"In all my years -- Classification of accounting services,"
Accounting Historians Journal: Vol. 3
, Article 2.
Available at: https://egrove.olemiss.edu/aah_journal/vol3/iss1/2