| Subject | English | Spanish |
| energ.ind. | non-renewable primary source of energy | energía primaria agotable |
| energ.ind. | primary energy source | fuente de energía primaria |
| light. | primary light source | fuente de luz primaria |
| earth.sc. | primary light source | fuente primaria de luz |
| work.fl. | primary sources | publicación primaria |
| gen. | primary sources | fuentes originales (Published and unpublished records without secondary interpretation or commentary) |