The phrase "overwhelmingly difficult" is correct and can be used in written English.
You can use it to describe something that is very difficult or hard to accomplish. For example, "The exam was overwhelmingly difficult and I was not able to finish it on time."
Anyone on first opening either book finds it overwhelmingly difficult and impenetrably obscure.
It has been overwhelmingly difficult for the carriers," said Mr. Balsillie.
But today, regulators may be unable to prosecute as many as half of the nation's largest known polluters because officials lack jurisdiction or because proving jurisdiction would be overwhelmingly difficult or time consuming, according to midlevel officials.
But midlevel E.P.A. officials said that internal studies indicated that as many as 45 percent of major polluters might be either outside regulatory reach or in areas where proving jurisdiction is overwhelmingly difficult.
Mrs. Hamilton said that when her husband was ill, his care was good, but no support services were available to her. "It was such an overwhelmingly difficult time in our lives," she said.
What we see here is a nationalist governor faced with an overwhelmingly difficult situation: 50% youth unemployment, 100,000 Catalan homes with no income whatsoever, a 60% increase in university fees, 40% of patients requiring urgent operation on waiting lists.
And I know the future will be overwhelmingly complex and difficult to navigate.
These are forms of private behavior that are both overwhelmingly important and extremely difficult to reach through conscious acts of intervention.
Replies that are overwhelmingly positive can be difficult to deconstruct in ways that are useful for service providers to translate into guides for service improvements [ 28].
As the outbreak of MDR TB/HIV co-infection in New York City in the mid-1990s theght the medical community, this co-infection is pernicious, difficult, and overwhelmingly expensive to treat.
Faced with a choice of the rumpled and resoundingly pro-Europe Clarke and the harder-edged approach of Duncan Smith, the faithful voted overwhelmingly for the latter, with difficult results.
