A combination of internal and external factors caused the company to close down.

内外因结合导致了公司的倒闭。

《牛津词典》

We can not be successful without the combination of the internal and external of the agent.

只有内因和外因相结合，才能到达成功的彼岸。

youdao

Managers' selection for university logistic service enterprise should insist on combination of internal training and external recommendation in order to strengthen enterprise's vitality.

高校后勤企业管理者选拔应坚持内部培养与外部引进相结合，增强企业活力。

youdao

The ultimate aim for Big Data is to incorporate multiple sets of data, (preferably) both proprietary (internal) data, with public (external) data and to discover insights into the business through a combination of hypotheses and analyses, augmented with intuition to generate new business innovation.

FORBES: Priorities 2013 -- Turning Data Into Insights