The phrase "a combination of external" is correct and usable in written English.
It can be used when discussing elements or factors that come from outside a particular system or context, often in a descriptive or analytical context.
Example: "The project's success was attributed to a combination of external factors, including market trends and consumer behavior."
Alternatives: "a mix of external" or "an amalgamation of external".
Five patients (8%) were treated by a combined treatment of external beam radiotherapy and chemotherapy, and one (2%) received a combination of external beam radiotherapy and biological therapy.
The IPCC attributes the recent slowing of surface temperatures to a combination of external and internal climate factors.
"I think a lot of dancers mature much too late because they're not able to find a combination of external mastery and internal light," he explained.
The recent volatility of the polling numbers, Mr. Fukuyama said, shows that a national crisis alone does not create trust in government: "It's a combination of external threats and government effectiveness.
But so far, a combination of external pressure from Western powers and internal dissent from liberal cabinet ministers appears to have persuaded Gen. Abdul-Fattah el-Sisi, the officer who ordered the takeover, to hold off decisive action.
But a combination of external and internal shocks the ousting of an elected president in Egypt and the second assassination this year of a leftist opposition politician at home has sent it off course.
Recent surveys have indicated that four alternatives are employed for adjuvant treatment of stage I endometrial adenocarcinoma: observation (OBS), high dose rate vaginal brachytherapy (VB), whole pelvic external beam radiotherapy (EBRT), or a combination of pelvic external beam with vaginal brachytherapy (COMB).
Boone (2010) and Westheimer (2008) argue that teachers are capable of compiling relevant learning material themselves and do not require external assistance, whereas Morris et al. (2003) consider a combination of both external and internal professional development to be most effective.
The company said a combination of "major external shock events" would cost the company at least £125m, while currency movements would cost it £90m, largely because of the sharp fall in the value of the pound since the Brexit vote on 23 June.
Increasing evidence indicates that a combination of elevated external forces (pressure and shear) and altered tissue properties is key to the etiology of foot ulcers.
Nevertheless, through a combination of fortuitous external circumstances and adroit diplomacy, it survived for another century, until finally conquered by the Ottomans in 1453.
