Sine wave generator

Hi,
I'm trying 2 analyse and simulate a circuit that is supposed to generate a sine wave..but, It generates a triangular wave instead!!!
I really dont know what may be wrong..
it is on the following website:
https://xoomer.virgilio.it/fladelle/Page13.htm

Can anyone help me with it,plzzz?
Thanks so much..

Looks like a Wien-bridge oscillator to me. Adjusting R5 controls the feedback and adjusting R5 carefully should produce a sine wave. If all
the componets are exact the frequency would be 1.06khz. Perhaps
you donot have the parts in the right part of the circuit.