the most effective way to combine sentences (11) and (12) is to use conjunction 'And' to connect both the two sentences.
Sentence number eleven "The league produced many fine players, including Mary “Bonnie” Baker.", and sentence number twelve "Dorothy Kamenshek was also a fine player.", both of them are depicting the same predicate of being 'fine'.
As we see, sentence eleven talks about producing 'fine' players including Mary "Bonnie" baker, and in sentence number twelve we see that the sentece say Dorothy Kamenshek was also a 'fine' player, which shows that both the sentences can be clubbed into one by just and a conjunction word "And".
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