The phrase "are multiple sources of" is correct and usable in written English.
It can be used when discussing various origins or references for information, data, or materials.
Example: "In our research, we found that there are multiple sources of information regarding climate change."
Alternatives: "there exist several sources of" or "there are various sources of".
There are multiple sources of danger for journalists.
I would simply say that in looking at this before the event and during the situation last night with the outage, there are multiple sources of power with redundancy, with good equipment.
"There are multiple sources of uncertainty," said Nathaniel Keohane, a former special assistant to President Obama for energy and environment, and now a vice president at the Environmental Defense Fund.
Undoubtedly, there are multiple sources of this residual disadvantage.
There are multiple sources of links to PubMed articles within PubChem and different contexts where they can be specified within a given PubChem record type.
In addition, fuel cell advocates point out that there are multiple sources of hydrogen, including hydro-electric or wind generators, nuclear power plants and natural gas.
Category 3 particles were divided into different types based on their chemical composition and determined that there could have been multiple sources of the category 3 particles, although some category 3 particles may have the same origin.
Based on the observations it appears that there have been multiple sources of the virus into the country during the early phase I outbreaks in India.
By contrast, no difference was found in the concentrations of sEndoglin between samples from non-pregnant women and from early pregnancy controls suggesting that there could be multiple sources of this protein.
As this study has a hierarchical design (i.e., where measurements will be taken on units across multiple experiments and over sequential time-points within an experiment), there will also be multiple sources of variation that need to be accounted for during analysis (such as 'between time-points within an experiment' and 'between experiments on the same unit').
There are multiple different sources of realistic non-white external noise.
