I am just an ordinary puthujana and I dare not acknowledge your salutation. It is most unusual that a Theravada monk is asking me a question, for I have been learning the Dhamma from monks. I am now in the most uncomfortable situation. I feel I am very disrespectful to you to answer your question. You are a bhante, my teacher. I pay my respect to you.
Be that as it may, to a follower of the Theravada tradition, the Theravada's text is the Tipitaka, then I would say, the complete teachings of the Buddha are to be found in it.
My respect to Bhante, bow.
Nowadays with the internet we are very fortunate to have comprehensive and reliable information on almost every subject. I can easilly search for Mahayana materials especially through www.buddhanet.net and www.wikepedia.
There are obvious differences between the two traditions. If you study the historical development of Buddhism after the mahaparinibbana of the Buddha, you will have a clearer picture. However, it is always a "sensitive" issue when we start comparing the two traditions and their differences. My humble opinion is that we concentrate on the similarities such as the Four Noble Truths, the Noble Eightfold Path, Tilakkana, Paticcasamuppada, and the Law of Kamma.
Mahayana suttas are distinct from the Tipitaka. They were from different sources. Again, which one do you want to refer? In the final analysis, it is up to the person to decide. No point indulging in debate and argument when we can practise the Dhamma in peace, which is the original purpose of practising Dhamma. Petty discussions on this issue have been going on for thousands of years. Do we want to be part of this foolish pursuit?
May I humbly suggest Bhante discuss the "issue" with your Sangha brothers.