@book{the+elements+of+machine+design+pt+2+chiefly+on+engine+details,
    author = {Unwin, William Cawthorne},
    title = {The elements of machine design. Pt. 2, Chiefly on engine details},
    address = {London i New York},
    publisher = {Longmans, Green},
    date = {1891}
}