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I am studying homological algebra by my self from Basic Homological algebra by M.Scott Osborne , I am having trouble to understand Theorem 3.9 page 56.

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My question is where can I find this Theorem in another reference like Rotman or others.

Any suggestion will be appreciated

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    I tried to add the theorem to the question. Is that what you were asking about? – 2017-02-10
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    This is used in the book to show the "balancing of Tor". One possible alternative reference with a similar proof is Weibel, "An introduction to homological algebra", section 2.7. – 2017-02-10
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    (There is a better, elegant way to get the balancing of Ext and Tor, but it's slighly outside of the context of your particular textbook; it uses the definition of derived functors as "universal $\delta$-functors".) – 2017-02-10
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    Thanks, Don ,which text book or notes online can I find it – 2017-02-10
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    For instance, see p. 15 here: http://www.math.lsa.umich.edu/~hochster/615W14/Tor.pdf – 2017-02-10

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