Matheus’:

1. Sign elements and elements compatibility.
Sources: 

- Wikipedia
- Astrology.about
- Mistérios Antigos - Translated from Portuguese

2. When a sign falls in love.
Source:

- Capricho Brasil - Translated from Portuguese

3. Compatibility Posts (See List)
Source: 

- Zodiac Facts Blog

4. About Signs.
Sources:

- Portal Terra - Translated from Portuguse.
- Café Astrology 
- O Guru - Translated from Portuguese

5. How signs kiss:
Source:

- O Guru - Translated from Portuguese

6. All the images I used:
Sources:

- We Heart It
- Google Images. 

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Caitlyn’s:

WEBSITE SOURCE(S):

http://www.iloveindia.com/astrology/

http://zodiac-signs-astrology.com/

http://www.astrology-online.com/

http://astro.cafeastrology.com/

BOOK SOURCE(S):

The Only Astrology Book You’ll Ever Need. by Joanna Martine Woolfolk.

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Steffany’s:

Online:

http://www.iloveindia.com/astrology/

http://zodiac-signs-astrology.com/

http://www.astrology-online.com/

http://astro.cafeastrology.com/

Offline:

Various magazines and my mother (a now retired astrologist)