TY  - RPRT
TI  - Preliminary summary of the ETF conceptual studies
AU  - Seikel, G. R.
AU  - Bercaw, R. W.
AU  - Pearson, C. V.
AU  - Owens, W. R.
PY  - 1978
UR  - https://ntrs.nasa.gov/citations/19790003307
ID  - 19790003307
ER  -