Can load network Rload=-Rout/3 rule be used for source network impedance?

Many sources mention than after oscillator power build up Rout (real part of output impedance) becomes less negative, so Rload=-Rout/3 value is used to ensure oscillations. What about Rin (real part of input impedance)? Can this principle also be applied at the input of oscillator? I mean can we use Rsource=-Rin/3 instead?

Terminator3 said:

so Rload=-Rout/3 value is used to ensure oscillations.

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This is for input of oscillator. Not output.

Thank for your reply! Can you give reference to your book?

"RF Circuit Design Theory and Applications, Second Edition" Reinhold Ludwig, Gene Bogdanov
page 475:

Usually, the power dependence of transistor's small-signal S-parameters results in a less negative Rout = Re(Zout) for increasing output power. Thus, it is necessary to choose Rl=Re(Zl) such that Rl+Rout<0. In practice, a value of Rl=-Rout/3 is often used.

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So it seems that rule can be used at any port, input or output.

Terminator3 said:

Can you give reference to your book?

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Very famous book on Microwave Engineering.
https://www.amazon.com/Microwave-En...ers&qid=1348984645&ref_=sr_1_3&s=books&sr=1-3

But I don't have 4th-edition.
I attached excerption from 3rd-edition.

Terminator3 said:

So it seems that rule can be used at any port, input or output.

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I think so.