The Mandozine Chord Book was created using the Chordsongs Web app. Downloads are available as individual PDF files by key, or all chords.
By learning the chord groups, you will have the basis for playing basic tunes in any key. It will also help in transposing to other keys by learning the universal key numbering system.
Learn to play mando chords up and down the neck. See the Fretboard pages for learning the fretboard notes to find the root note for the movable chords.
Here's an on-line chord resource by chord type.
These Mandolin Practice Sheets by Charlie Jones are in PDF format and cover the keys of C, G, D, A and E. These sheets provide a "drill" sheet that players can use to build up playing dexterity.
Abbreviated Chords for Mandolin by Charlie Jones.