Harbrace 6a(2): Make the subject and verb agree when words intervene between them.
The rhythm of the pounding waves is calming.
All of the dogs in the neighborhood were barking.
The grammatical number of the subject does not change with the addition of expressions beginning with such words as accompanied by, along with, as well as, in addition to, including, no less than, not to mention, together with.
The economy as well as taxes influences votes.
Taxes, not to mention unemployment, influence votes.
Things get peskier in different kinds of contructions. For example, here is a photo caption from a News Sentinel article about Mintha Roach, the Knoxville Utility Board's president and chief executive officer: "Roach is one of three women in the nation who heads a public utility."
In this case, the "who" clause modifies "three women," so the verb should be the plural "head." There are many other times that a prepositional phrase simply modifies the subject of a sentence, as in the cases from Harbrace above.