Two different views on the origins of the Mahayana

SGI's view: Who Composed the Mahāyāna Scriptures? – The Mahāsāṃghikas and Vaitulya Scriptures* by Seishi KARASHIMA, 

http://iriab.soka.ac.jp/content/pdf/aririab/Vol.%20XVIII%20(2015).pdf
[scroll down to pg.113]

Nichiren's and our view: The Origins and Nature of Mahayana Buddhism by Paul Williams:

https://books.google.com/books?id=ypH36xRFZ9kC&pg=PA182&lpg=PA182&dq=Sarv%C4%81stiv%C4%81dins+and+the+mahayana&source=bl&ots=4G8d8O5467&sig=hMYKxsUgrCXkdLXwFWPE-TFrLTM&hl=en&sa=X&ved=0CCwQ6AEwA2oVChMIs-fQ_IHLyAIVCiuICh2zywJE#v=onepage&q=Sarv%C4%81stiv%C4%81dins%20and%20the%20mahayana&f=false