The reason given for doubting that we have a true record of the Buddhas teaching the absence of a written record, is actually a great strength. Because they were commited to memory, and not modern scattered memory, but the memory of those who had been trained in memorisation from early childhood. And then repeated continously down the centuries with the old men making sure that the repetition was correct, it was communal not a matter of individual endevour with pen and ink. Its repetition has not altered in the last hundred years , there is no reason to suspect that it changed in the first hundred years.
The going for refuge is the door of entrance to the teachings of the Buddha.