@book{the+elements+of+machine+design+pt+1+general+principles+fastenings+and+transmissive+machinery,
    author = {Unwin, William Cawthorne},
    title = {The elements of machine design. Pt. 1, General principles, fastenings, and transmissive machinery},
    address = {London i New York},
    publisher = {Longmans, Green},
    date = {1890}
}