The department of labor estimates that there is about 4,100,00 secretaries in the workforce so know secretary should feel he is alone ^turn this sentence into formal english

No secretary should feel alone for the reason that there are around 4,100,000 secretaries in the workforce.

the National Science Foundation

The website publisher that  would be considered an authoritative source about the cultures of ancient Mesopotamia is the National Science Foundation because it uses a scientific apporach with peer reviewed articles that assure that the sources used are legitimate and trustworthy, while the other sites could not assure this principle.

Fact Monster

the least biased websites is fact monster, because it does not have to respond to any party or association that coud dictate its opinion in one way or the other, while the other sites in the list could propose thesis influenced either by their political views or by their economic interests in the subject discussed.