I noted your call for the publication data of a Legendary Service Literature, the details that you require for your model "20" tractor are : - Manual publication date 1st May 1930, Form No SL1833, number of pages 118, and overall size is 6 inches x 9 inches. Address is Caterpillar Legendary Service Literature, Midland Press Corp, 5540 Corporate Park Drive, Davenport, Iowa. 52807. Phone 1-(800)-228-7821, Fax- 1- (319)-355-3690. Your tractor was built during the 1930 production year. Hope that this is of help to you.