##### CORRECTIONS AND FURTHER REFERENCES FOR

### George M. Bergman
*Coproducts and some universal ring constructions,*
Trans. A.M.S. 200 (1974) 33-88

P.43: In the display, the equation defining
*P*_{2} should be:
*P*_{2} = Im(1-*e*) = Ker(*e*).

P.50: The last line ("nonzero powers ...") should instead be the
last line on p.51.

P.52: In the third line of the proof of Theorem 6.4,
the statement that direct limits respect the property of being
semihereditary is incorrect; see [35, Example 4.2].
However [35, Theorem 3.4] leads to a stronger result
than that of the abovementioned theorem; namely,
that Theorem 6.2 holds without the finite generation condition.

Pp.68-75, sections 10-11:
most of the questions raised in these sections are answered in [35].

Notes on the other papers listed below: [34] is closely related
to [35], though the latter does not depend on it.
[36] gives an example stronger than that of Example 10.2 of this paper,
which also answers the question in the paragraph before that example.
[37] inter alia corrects an error in [18].

### Additional references (continuing numbering in paper)

[34] George M. Bergman and Warren Dicks,
*On universal derivations*, J. Alg. **36** (1975) 193-211.
MR52#8196.

[35] George M. Bergman and Warren Dicks,
*Universal derivations and universal ring constructions*,
Pacific J. Math. **79** (1978) 293-337. MR81b:16024.

[36] Robert A. Indik,
*A PI-algebra which is not PI when an inverse is adjoined*,
Proc. A. M. S. **76** (1979) 11-13. MR80d:16015.

[37] P. M. Cohn and Warren Dicks,
*Localization in semifirs, II*, J. London Math. Soc.
(2) **13** (1976) 411-418. MR54#12814.

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